[Senate Hearing 108-1020]
[From the U.S. Government Publishing Office]







                                                       S. Hrg. 108-1020

                           NEAR EARTH OBJECTS

=======================================================================

                                HEARING

                               before the

                 SUBCOMMITTEE ON SCIENCE, TECHNOLOGY, 
                               AND SPACE

                                 of the

                         COMMITTEE ON COMMERCE,
                      SCIENCE, AND TRANSPORTATION
                          UNITED STATES SENATE

                      ONE HUNDRED EIGHTH CONGRESS

                             SECOND SESSION

                               __________

                             APRIL 7, 2004

                               __________

    Printed for the use of the Committee on Commerce, Science, and 
                             Transportation



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       SENATE COMMITTEE ON COMMERCE, SCIENCE, AND TRANSPORTATION
       

                      ONE HUNDRED EIGHTH CONGRESS

                             SECOND SESSION

                     JOHN McCAIN, Arizona, Chairman
TED STEVENS, Alaska                  ERNEST F. HOLLINGS, South 
CONRAD BURNS, Montana                    Carolina, Ranking
TRENT LOTT, Mississippi              DANIEL K. INOUYE, Hawaii
KAY BAILEY HUTCHISON, Texas          JOHN D. ROCKEFELLER IV, West 
OLYMPIA J. SNOWE, Maine                  Virginia
SAM BROWNBACK, Kansas                JOHN F. KERRY, Massachusetts
GORDON H. SMITH, Oregon              JOHN B. BREAUX, Louisiana
PETER G. FITZGERALD, Illinois        BYRON L. DORGAN, North Dakota
JOHN ENSIGN, Nevada                  RON WYDEN, Oregon
GEORGE ALLEN, Virginia               BARBARA BOXER, California
JOHN E. SUNUNU, New Hampshire        BILL NELSON, Florida
                                     MARIA CANTWELL, Washington
                                     FRANK R. LAUTENBERG, New Jersey
      Jeanne Bumpus, Republican Staff Director and General Counsel
             Robert W. Chamberlin, Republican Chief Counsel
      Kevin D. Kayes, Democratic Staff Director and Chief Counsel
                Gregg Elias, Democratic General Counsel
                                 ------                                

             SUBCOMMITTEE ON SCIENCE, TECHNOLOGY, AND SPACE

                    SAM BROWNBACK, Kansas, Chairman
TED STEVENS, Alaska                  JOHN B. BREAUX, Louisiana, Ranking
CONRAD BURNS, Montana                JOHN D. ROCKEFELLER IV, West 
TRENT LOTT, Mississippi                  Virginia
KAY BAILEY HUTCHISON, Texas          JOHN F. KERRY, Massachusetts
JOHN ENSIGN, Nevada                  BYRON L. DORGAN, North Dakota
GEORGE ALLEN, Virginia               RON WYDEN, Oregon
JOHN E. SUNUNU, New Hampshire        BILL NELSON, Florida
                                     FRANK R. LAUTENBERG, New Jersey
                                     
                                     
                                     
                                     
                                     
                                     
                                     
                                     
                                     
                                     
                                     
                                     
                                     
                                     
                                     
                                     
                                     
                                     
                                     
                                     
                                     
                                     
                                     
                                     
                                     
                                     
                                     
                                     
                                     
                            C O N T E N T S

                              ----------                              
                                                                   Page
Hearing held on April 7, 2004....................................     1
Statement of Senator Brownback...................................     1

                               Witnesses

Citters, Dr. Wayne Van, Director, Division of Astronomical 
  Sciences, National Science Foundation..........................     7
    Prepared statement...........................................     9
Griffin, Michael D., Head of the Space Department, Applied 
  Physics Lab, Johns Hopkins University..........................    29
    Prepared statement...........................................    31
Johnson, Dr. Lindley N., Program Scientist, Near Earth Object 
  Observation Program, National Aeronautics and Space 
  Administration.................................................    11
    Prepared statement...........................................    13
Lu, Dr. Edward, NASA Astronaut and President, B612 Foundation....    35
    Prepared statement...........................................    37
Schweickart, Dr. Russell L., Chairman of the Board, B612 
  Foundation.....................................................    39
    Prepared statement...........................................    41
Stokes, Dr. Grant H., Chairman, Near Earth Object Science 
  Definition Team, MIT Lincoln Laboratory........................    23
    Prepared statement...........................................    25

                                Appendix

Rohrabacher, Dana, Congressman (R-CA), prepared statement........    59
 
                           NEAR EARTH OBJECTS

                              ----------                              


                        WEDNESDAY, APRIL 7, 2004

                               U.S. Senate,
    Subcommittee on Science, Technology, and Space,
        Committee on Commerce, Science, and Transportation,
                                                    Washington, DC.
    The Committee met, pursuant to notice, at 2:30 p.m. in room 
SR-253, Russell Senate Office Building, Hon. Sam Brownback, 
presiding.

           OPENING STATEMENT OF HON. SAM BROWNBACK, 
                    U.S. SENATOR FROM KANSAS

    Senator Brownback. The hearing will come to order. Thank 
you all very much for coming today. My apologies for being 
nearly a half hour late. We had two votes scheduled back to 
back and I had to go over and vote. I apologize for that to our 
witnesses and to others.
    We appreciate people being able to come particularly on 
this Holy Week of Passover and Easter. It's quite a week and I 
appreciate our witnesses are willing to come into town for this 
particular important hearing that we're having.
    Most people have watched Hollywood movies about asteroids, 
or more correctly ``Near-Earth Objects''--NEOs for short--
striking the Earth. Yet few know what is real and what is not. 
Fewer still know what your government is doing about this 
threat, or not doing for that matter.
    Asteroid 2004FH, approximately 100 feet wide, passed within 
about 25,000 miles of the Earth on March 18, 2004. This is 
equivalent to riding in an airliner and seeing a small plane 
suddenly pass a few hundred feet off the wing. It's a pretty 
scary occurrence. Had this asteroid hit the Earth, as a 
somewhat bigger one did in 1908, it would have released over a 
megaton of energy. This is the explosive yield of a large 
nuclear weapon. Yet we had only a few days warning of Asteroid 
2004FH. Other similar objects just missed us in the past few 
years and we didn't even see them until they were past.
    Scientists tell us that a big asteroid, ten miles in 
diameter, destroyed the dinosaurs 65 million years ago. 
Asteroids are the small bits left over from the formation of 
the solar system billions of years ago. If we look up at the 
moon we can see the results of billions of years of bombardment 
in its shattered face. The Earth suffered similar hits but most 
have healed due to Earth's weather and geological processes.
    Small asteroids hit the Earth every year; about thirty 
struck the upper atmosphere last year. They each release as 
much energy as a small atomic bomb. Fortunately the atmosphere 
protects us from these little asteroids. But ones such as the 
March 18 object could devastate a large city. Experts tell us 
that we run about the same risk of dying in an airline crash as 
we do dying from an asteroid strike. This is serious and 
warrants serious attention by our government.
    The President's new space exploration vision mandates that 
we focus our attention on the opportunities inherent in moving 
human presence into the solar system. But it also raises the 
question as to potential threats out there. Panels of experts 
have met over the past few years. All tell us that the threat 
of NEO impact is real. At the smallest scale, those that strike 
us several times a month could be confused in a crisis as a 
nuclear attack. Asteroids the size of the one a few weeks ago 
hit Earth several times a century. The experts also tell us 
that we could have the ability to detect these objects before 
they hit and do something about it.
    Today we are meeting to consider whether Congress should 
pass legislation to do something about this threat from space. 
We will hear from program managers within NASA and the National 
Science Foundation on what is being done now and what is 
planned.
    We will hear from the experts in our scientific community 
on what they recommend we do to find the threatening objects 
before they hit. We will hear from space development experts on 
how we could build spacecraft quickly and cheaply to meet 
threatening objects deep in space to find out about them and 
divert them as necessary.
    And finally, we will hear from former and current 
astronauts how these objects might fit into the President's 
exciting new space exploration vision, both as targets for 
scientific exploration and commercial use, as well as how to 
divert the threatening ones.
    For the first time in this planet's long history, the life 
that lives here can take control of its own long-term destiny 
in this regard. The clockwork of the solar system eliminated 
dinosaurs. Humans were one result of that event. The question 
before us is to whether and how humans will deal with this 
aspect of our collective future.
    I want to enter into the record then as well, a statement 
from Congressman Dana Rohrabacher who could not be here with us 
today. They are on break on the House side and he has proposed 
a bill to deal with Near Earth Objects and that will be put 
into the record.
    [The information referred to follows:]


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    Senator Brownback. I'm delighted you all could join us 
today. I look forward to this informative hearing giving the 
Senate some idea of what all is being done and what needs to be 
done.
    Our first panel is Dr. Wayne Van Critters--Citters?
    Dr. Van Citters. Van Citters.
    Senator Brownback. Van Citters, excuse me. That's a near 
miss for me on the pronunciation. Division Director, Division 
of Astronomical Sciences, National Science Foundation. I'm 
delighted you're here.
    Dr. Lindley Johnson, Program Manager, Near Earth Objects 
Observation Program at NASA.
    Gentlemen. We're delighted to have both of you here. I 
apologize for being late. Your full statement will be placed in 
the record and so you're free to summarize or to present 
however you'd like to. Dr. Van Citters.

         STATEMENT OF DR. WAYNE VAN CITTERS, DIRECTOR,

               DIVISION OF ASTRONOMICAL SCIENCES,

                  NATIONAL SCIENCE FOUNDATION

    Dr. Van Citters. Thank you sir. Chairman Brownback, Ranking 
Member Breaux, and distinguished Members of this Subcommittee.
    We appreciate the opportunity to present the position of 
the National Science Foundation on the important subject of 
Near Earth Objects this afternoon and in responding, I'll 
present a picture of NSF's current activities in this area. We 
are supporting research into the nature and origin of these 
objects as well as potential important contributions that NSF 
support, instrumentation and techniques could make to an 
expanded discovery and characterization effort.
    As I'm sure the Committee is aware, NSF supports a wide 
range of basic research in astronomy from solar system studies 
to cosmology all the way to the very nature of matter and 
energy and what we support is driven by the interest of the 
scientific community that we support and our merit review 
process.
    The Committee is probably also aware of the formation of 
the Astronomy and Astrophysics Advisory Committee. This is 
after the study that was done on possibly combining 
astronomical research at NSF and NASA and the purpose of this 
Committee is to advise both NSF and NASA and to some extent DOE 
on areas of common interest and cooperation. And in this recent 
March 15 report, the first report that this Joint Advisory 
Committee made, they underscored along with a number of other 
issues the number and nature of Near Earth Objects as an 
important and fundamental question to be investigated over the 
coming decade.
    We support a wide range of individual investigator grants 
and operations at Arecibo, the National Astronomical and 
Ionospheric Center, in particular the Planetary Radar Program 
there, and these investigations look at the nature of Near 
Earth Objects and I've given a few examples of those 
investigations in the written testimony.
    In general, they concentrate on the internal structure and 
origin of the objects whether they're binary in nature. If they 
are binary or multiple in nature, how that came to be and for 
some of the brighter ones, with more modern instrumentation or 
even capable of doing some rather detailed mineralogical 
analysis of the actual composition of the objects themselves.
    We've seen an increasing interest in this area in the 
scientific community through the proposals presented to us over 
about the past 2 to 3 years and are making choices of which 
areas to support through our normal merit review of the 
proposals.
    Looking to the future. I detailed in the statement the 
results of the NASA study which was reported out in late 2002, 
I believe, which outlines the current status of the Space Guard 
Program which I'm sure Lindley will talk about in much more 
detail and recommends next steps.
    Very briefly, this treats the post-2008 period and in its 
conclusions urges that a catalogue of objects larger than 140 
meters in diameter, so considerably larger than the one that 
passed by us a few weeks ago, be completed which would give a 
complete census at about the 90 percent certainty level.
    The study estimates that the same approaches would provide 
60 to 90 percent uncertainty--or 60/90 percent completion for 
objects larger than 50 meters. An object of this size would 
provide quite a large air burst but not anything like a 
dinosaur extinction event.
    The study sets out several approaches both ground and space 
based to consider in reaching the above goal and it gives a 
cost and benefit analysis. So we think it provides a rather 
solid basis for looking at how to go forward in the future.
    In that regard, our plans at NSF we are considering 
building on that NASA study and charging a Subcommittee of our 
Joint Astronomy and Astrophysics Advisory Committee with 
looking at an appropriate effort following on the Space Guard 
effort that would span both agencies and in particular for NSF 
how we would increase our ground based effort in this area.
    We would foresee that it would certainly involve an 
increase in the support of individual investigator efforts 
looking into the nature and origin of the object themselves 
provided that our community interests and the proposal quality 
warrants it.
    It would also however I think look at what's being proposed 
and highly rated in three of the National Research Council and 
the Department of Defense looking at trade studies and relative 
merit of these two possible instrumentation efforts for 
contributions to the future of the detection effort. And in 
particular there are estimates that the LSST and possibly Pan-
STARRS could indeed respond to the challenge of cataloguing all 
of the 140 meter diameter or larger asteroids within seven to 
twenty years.
    In conclusion, we're pursuing a significant amount of basic 
research in this area and we are laying plans for new 
facilities and expanded research activity that speak to many of 
the basic questions about the objects themselves and are 
confident that the body of knowledge that we gain by this 
effort will have important application to any eventual risk 
mitigation effort.
    Again, I thank you for the opportunity to appear and we'd 
be happy to respond to any questions.
    [The prepared statement of Dr. Van Citters follows:]

     Prepared Statement of G.W. Van Citters, Director, Division of 
           Astronomical Sciences, National Science Foundation
    Chairman Brownback, Ranking Member Breaux, and distinguished 
members of the Subcommittee. Thank you for the opportunity to present 
the position of the National Science Foundation on the important 
subject of Near Earth Objects. In responding to the questions that the 
Committee has presented to us, I will present a picture of NSF's 
support of research into the nature and origin of these objects, as 
well as potential important contributions that NSF-supported 
instrumentation and techniques could make to an expanded discovery and 
characterization effort.
Background and Context
    The Division of Astronomical Sciences supports basic research in 
astronomy covering a very wide range of subjects--from studies of 
objects in our own solar system to investigations of the beginning of 
the universe, including the very nature of matter and energy. In 
planning and conducting its programs, the Division benefits from the 
advice of the scientific community in many ways, including the recently 
established Astronomy and Astrophysics Advisory Committee (AAAC, 
jointly advising NSF, NASA, and DOE). The establishment of the AAAC 
recognizes the value of an integrated strategy to address national 
efforts to answer questions about our origins and our future. The 
number and nature of NEOs are clearly fundamental questions about both 
our origins and our future. In their March 15, 2004 report the AAAC 
recommended a coordinated implementation effort to ensure timely 
development of the Large Synoptic Survey Telescope, calling it a key 
facility for the detection of potentially hazardous earth-intersecting 
objects as small as 300 meters.
Current Activity
    A number of awardees in our Planetary Astronomy Program are 
investigating Near Earth Objects (NEOs). The proposals funded by our 
program are determined by the interest of the research community, as 
reflected in the number and subject matter of proposals that we 
receive, and the results of our merit review of these proposals.
    As one example, Dr. Derek Richardson at the University of Maryland 
will be modeling the tidal disruption of near Earth asteroids (NEAs) by 
the Earth's gravitational field to determine the frequency of binary 
NEA formation and the typical characteristics of the resulting binary 
asteroids. The results from this research will give insight into the 
internal structure of NEAs and may have implications for hazard 
mitigation strategies.
    In another effort, Richard Binzel at MIT will measure the near-
infrared spectral properties of 40-60 NEOs per year. The observations 
will balance measurements that push the state-of-the-art limits of the 
technology for the smallest and faintest objects and measurements that 
provide sufficient detail for detailed mineralogical analysis.
    Research in this area also represents a substantial fraction of the 
use of the Arecibo planetary radar system, characterizing sizes, 
shapes, rotation rates, and configurations (single or binary, e.g.). 
The smallest system yet observed (a binary of 120m and 40 m diameter 
components) was discovered in 2003. Measurements from a combination of 
Arecibo and NASA's Goldstone antenna from 1991 through 2003 
demonstrated the existence of the Yarkovsky effect. This effect is an 
acceleration of the body related to the time delay between the 
absorption of solar radiation and the re-emission in the infrared. The 
observations clearly indicated that the acceleration must be included 
in orbit predictions.
    We have observed that the number of proposals to investigate NEOs 
has been increasing annually for the last few years. Of the proposals 
we receive on this topic, those that do best in our merit review 
competition are those proposing to characterize the physical properties 
of the objects. What are they made of? How were they formed and when?
    I believe NSF is currently playing the role for which it is best 
suited. It is funding individual investigators to further our 
understanding of the physical make-up of NEOs. The proposals for these 
investigations are subject to our normal merit review, thus insuring 
high quality basic research on these objects. In addition, it provides 
access to tools such as Arecibo that can enhance the discovery process.
Looking to the Future
    In recent years, there has been an increasing appreciation for the 
hazards posed by near-Earth objects, those asteroids and periodic 
comets (both active and inactive) whose motions can bring them into the 
Earth's neighborhood. In August of 2002, our colleagues at NASA 
chartered a Science Definition Team to study the feasibility of 
extending the search for near-Earth objects to smaller limiting 
diameters. The formation of the team was motivated by the good progress 
being made toward achieving the Spaceguard goal of discovering 90 
percent of all NEOs with diameters greater than 1 km by the end of 
2008. This raised the question of what, if anything, should be done 
with respect to the much more numerous smaller, but still potentially 
dangerous, objects. The team was tasked with providing recommendations 
to NASA as well as the answers to seven specific questions. We believe 
that the answers to these questions could form a solid basis for the 
direction of our research efforts and for more detailed studies of the 
best integrated strategy to carry on at the end of Spaceguard in 2008.

        What are the smallest objects for which the search should be 
        optimized? The Team recommends that the search system be 
        constructed to produce a catalog that is 90 percent complete 
        for potentially hazardous objects (PHOs) larger than 140 
        meters.

        Should comets be included in any way in the survey? The Team's 
        analysis indicates that the frequency with which long-period 
        comets (of any size) closely approach the Earth is roughly one-
        hundredth the frequency with which asteroids closely approach 
        the Earth and that the fraction of the total risk represented 
        by comets is approximately 1 percent. The relatively small risk 
        fraction, combined with the difficulty of generating a catalog 
        of comets, leads the Team to the conclusion that, at least for 
        the next generation of NEO surveys, the limited resources 
        available for near-Earth object searches would be better spent 
        on finding and cataloging Earth-threatening, near-Earth 
        asteroids and short-period comets. A NEO search system would 
        naturally provide an advance warning of at least months for 
        most threatening long-period comets.

        What is technically possible? Current technology offers 
        asteroid detection and cataloging capabilities several orders 
        of magnitude better than the presently operating systems. This 
        report outlines a variety of search system examples, spanning a 
        factor of about 100 in search discovery rate, all of which are 
        possible using current technology. Some of these systems, when 
        operated over a period of 7-20 years, would generate a catalog 
        that is 90 percent complete for NEOs larger than 140 meters.

        How would the expanded search be done? From a cost/benefit 
        point-of-view, the report concludes that there are a number of 
        attractive options for executing an expanded search that would 
        vastly reduce the risk posed by potentially hazardous object 
        impacts. The Team identified a series of specific ground-based, 
        space-based and mixed ground-and space-based systems that could 
        accomplish the next generation search. The choice of specific 
        systems would depend on the time allowed for the search and the 
        resources available.

        What would it cost? For a search period no longer than 20 
        years, the Team identified several systems that they felt would 
        eliminate, at varying rates, 90 percent of the risk for sub-
        kilometer NEOs, with costs they estimate to range between $236 
        million and $397 million for both ground and space components. 
        They conclude that all of these systems have risk reduction 
        benefits which greatly exceed the costs of system acquisition 
        and operation.

        How long would the search take? The Team concludes that a 
        period of 7-20 years is sufficient to generate a catalog 90 
        percent complete to 140-meter diameter, which will eliminate 90 
        percent of the risk for sub-kilometer NEOs. The specific 
        interval would depend on the choice of search technology and 
        the investment allocated.

        Is there a transition size above which one catalogs all the 
        objects, and below which the design is simply to provide 
        warning? The Team concluded that, given sufficient time and 
        resources, a search system could be constructed to completely 
        catalog hazardous objects with sizes down to the limit where 
        air blasts would be expected (about 50 meters in diameter). 
        Below this limit, there is relatively little direct damage 
        caused by the object. Over the 7-20 year interval (starting in 
        2008) during which the next generation search would be 
        undertaken, the Team suggests that cataloging is the preferred 
        approach down to approximately the 140-meter diameter level and 
        that the search systems would naturally provide an impact 
        warning of 60-90 percent for objects as small as those capable 
        of producing significant air blasts.

    The path from where we are today to where we should be in 2014 is 
not defined in the conclusions of the study that NASA sponsored. Clear 
goals are defined; how one might reach them is wisely left to the 
scientific and technical community. At the national level, we must now 
examine these goals in detail, validate the conclusions, and determine 
how they might best be achieved.
NSF Plans for the Future
    We are considering asking the AAAC to form a subcommittee to advise 
on the effort that would be appropriate beyond Spaceguard. Broadly 
based in the scientific and technical community, this subcommittee 
would consider the conclusions of recent studies, extract necessary 
research directions that would help us better understand the origin and 
nature of the objects known to date and help to chart the most 
productive course into the future. By the very nature of the charge to 
the AAAC, this would be an integrated look at the ground-based and 
space-based efforts that would make the most effective scientific 
advances in this area.
    Of particular interest to NSF would be the expansion of the 
individual investigator-driven basic research that we currently 
support, and a more detailed understanding of how such projects as the 
Large Synoptic Survey Telescope (LSST) and Panoramic Survey Telescope 
and Rapid Response System (Pan-STARRS) might best contribute to the 
discovery and characterization effort in the future.
    The LSST is a proposed single 8.4meter aperture, very wide field 
telescope capable of surveying the entire sky visible from one 
hemisphere every two weeks. It has a variety of science drivers 
including the characterization of dark matter and dark energy, the 
discovery of many classes of transient objects such as supernovae and 
gamma-ray burst counterparts, and NEOs.
    Pan-STARRS, an Air Force funded project under construction in 
Hawaii, will be composed of 4 individual telescopes of 1.8meter 
aperture observing the same region of sky simultaneously. In survey 
mode, i.e., searching for NEOs, Pan-STARRS will cover 6,000 square 
degrees per night. The whole available sky as seen from Hawaii will be 
observed 3 times during the dark time in each lunation.
    The LSST's ability to make fast, wide, and faint observations may 
make it uniquely suited to detecting small NEOs. A model LSST survey 
covering 9,000 square degrees of sky along the ecliptic, three or four 
times a month, to a limiting V magnitude of 24.0, achieved a ten-year 
completeness of about 90 percent for NEOs larger than 250 m, and about 
80 percent for NEOs down to 140 m as called for by the NASA study. The 
requirements placed on the telescope, telescope operations, data system 
and detectors by the NEO detection challenge are considerable.
    By reaching objects 100 times fainter than those currently observed 
in the NEO surveys, Pan-STARRS is being designed to help complete the 
Congressional mandate to find and determine orbits for the 1-km (and 
larger) threatening NEOs. Further, it should push the detection limit 
for a complete (99 percent) sample down to objects as small as 300-
meters in diameter.
    Design studies over the next several years will be needed to 
determine the strategy for attacking the NEO problem and whether it is 
best carried out with a single telescope like the LSST or whether an 
array of smaller telescopes such as Pan-STARRS is more appropriate for 
this particular problem. NSF's Division of Astronomical Sciences has 
begun planning for such studies and we have been actively joined by our 
colleagues at NASA, who will contribute their knowledge and experience 
in the handling of large data bases and archives.
Conclusion
    In conclusion, Mr. Chairman, NSF is already pursuing a significant 
amount of basic research in this important area. We are guided, as 
always, by the scientific community through our merit review process. 
We are laying plans for new facilities and expanded research activity 
that speak to many basic questions about the nature and origin of these 
objects, and are confident that the body of knowledge so gained will 
have important application to any eventual risk-mitigation effort.
    Again I thank you for the opportunity to appear and would be happy 
to respond to any questions.

          STATEMENT OF DR. LINDLEY N. JOHNSON, PROGRAM

  SCIENTIST, NEAR EARTH OBJECT OBSERVATION PROGRAM, NATIONAL 
              AERONAUTICS AND SPACE ADMINISTRATION

    Dr. Johnson. Thank you, Mr. Chairman, for the opportunity 
to present to the Subcommittee information on this important 
subject on NEOs.
    At the request of Congress, NASA conducts the NEO 
observation program to research the population of the larger 
asteroids and periodic comets that pass relatively close to the 
Earth and may one day pose a collision hazard with our planet. 
Our NEO program has been quite successful in finding these 
larger objects in the first 5 years of its effort.
    In the effort to gain a better understanding of this 
hazard, NASA's Office of Space Science has been conducting a 
search of space near the Earth's orbit to understand the 
population of objects that could do significant damage to the 
planet should there be a collision.
    Commonly referred to as a ``Space Guard Survey,'' this 
research seeks those asteroids and periodic comets that come 
within an astronomically close 50 million kilometers of the 
Earth. The objective of this survey is to detect within a 10-
year period at least 90 percent of the NEOs that are greater 
than one kilometer in size and predict their orbits into the 
future.
    Currently, slightly over 4 million per year is budgeted for 
the program. This funds modest search efforts, typically using 
refurbished ground based telescopes of about one meter aperture 
and wide field of view coupled with digital imaging in order to 
cover significant portions of the sky each month.
    Presently 5 NEO search projects are either wholly or 
largely funded with this resource. Also important to the effort 
is the observation correlation and initial orbit determination 
done by the Minor Planet Center which is operated by the 
Smithsonian Astrophysical Observatory and the High Accuracy 
Orbit Propagation and Project Coordination done by NASA's NEO 
Project Office at the Jet Propulsion Lab.
    The chart you've been handed summarizes the progress to 
date in finding the Near Earth Asteroids or NEAs greater than 
one kilometer in size. The program continues to make steady 
progress since it started in 1998 to the goal of finding at 
least 90 percent of these NEOs. As of the end of March, 514 of 
the 702 known NEAs determined to be larger than one kilometer 
have been found by the program out of an estimated total 
population of about 1,100.
    We have also found 11 of 49 known Earth approaching comets. 
In addition, 1,866 of the 2,032 known Near Earth Asteroids of 
smaller size have been found. Because the projects are always 
refining the detection techniques, the discovery of smaller 
objects is becoming more frequent.
    None of these objects found to date are on impact 
trajectories with the Earth in the next 100 years.
    The results of the recent study by the Science Definition 
Team which Dr. Van Citters referred to which was commissioned 
by my office and you'll hear more about it from Grant Stokes, 
will show that it is entirely appropriate that we search for 
the larger NEOs first, because all factors considered, that is 
where the greatest risk from an undetected asteroid on an 
impact trajectory lies. This is principally due to the 
worldwide devastation it would cause. It is orders of magnitude 
above what a smaller few hundred meter sized impact would 
create and could well disrupt human civilization for decades 
after an impact.
    Completion of the current effort to find these large 
objects will do much to reduce this uncertain risk and find the 
objects many decades before any impact threat. But until the 
total population of these objects is known, there is always the 
chance that an object bound for a near term impact maybe 
discovered similar to the real life scenario which unfolded 10 
years ago, when comet Shoemaker-Levy 9, was discovered only in 
March 1993 inbound for a July 1994 impact on Jupiter.
    It should be understood that the NEO Observation Program is 
merely a science survey and does not provide a leakproof 
warning network for impact of any size natural object large or 
small. Such a comprehensive network would require an order of 
magnitude increase in our funding and the cooperative efforts 
of several government departments and agencies like with NSF.
    Operational experience with the current system shows that 
for every one kilometer of greater size asteroid found, there 
are three to four smaller size asteroids also discovered.
    But the true ratio of the small to larger asteroids is 
thought to be over 100 to one. Because of the limitations of 
the current search systems, the discovery of smaller asteroids 
is only possible in a significantly smaller volume around the 
Earth. If our sensors can detect a one kilometer sized asteroid 
at 50 million kilometers, they can also see a 100 meter 
asteroid, but at perhaps only half a million kilometers or a 
little beyond the moon's orbit.
    But at planetary orbital velocities, if the object is on 
impact trajectory of the Earth, it would cover even this 
distance in less than a day.
    Thus, the detection of a relatively small asteroid on a 
destiny with Earth could also come with relatively short 
reaction time. The impact of a 100 meter asteroid on Earth 
could do significant damage at the surface as this is estimated 
to result in an approximately a 50 megaton energy release at or 
perhaps slightly above the surface. This will result in much 
loss of life if the impact were in a populated area.
    It is therefore prudent that we begin to put into place 
contingency plans such as an internal NASA notification plan we 
are drafting to deal with such a relatively unlikely but 
extremely high consequence event.
    Thank you for the opportunity to speak at this hearing and 
I'd be happy to respond to any questions you have.
    [The prepared statement of Dr. Johnson follows:]

Prepared Statement of Lindley N. Johnson, Program Scientist, Near Earth 
      Object Observation Program, National Aeronautics and Space 
                             Administration
    Thank you, Mr. Chairman, for the opportunity to present to the 
subcommittee information on the important subject of Near Earth 
Objects. At the request of Congress, NASA conducts the Near Earth 
Object (NEO) Observation Program to discover the larger sized asteroids 
(greater than 1 kilometer or 0.62 miles in size) and periodic comets 
that pass relatively close to the Earth and may one day pose a 
collision hazard with our planet. Our NEO program has been quite 
successful in finding these larger objects in the first five years of 
the effort.
Background
    The Earth orbits about the Sun in a cloud of planetary debris still 
left from the formation of the Solar System. This debris ranges from 
micron-sized dust particles, to meteoroids at sand grain to a few 
meters in size, and to asteroids and comets that are tens of meters to 
several kilometers in dimension. Collision with meter-sized meteoroids 
is almost a weekly event for the Earth, but the surface is well 
protected from these common events by its atmosphere, which will cause 
objects less than about 50 meters in size and of average density to 
disintegrate harmlessly before reaching the ground. However, even the 
relatively active surface of the Earth still bears scars of impacts 
from space, with 168 craters worldwide--some up to 300 kilometers in 
size--having been identified to date.
    Though collisions with larger bodies are much less frequent now 
than in the early stages of planet formation in the Solar System, they 
do still occur. Very significant events, capable of causing damage at 
the surface, will happen on scales of a few hundred to a thousand 
years. But we do not know when the next impact of an object of 
sufficient size to cause widespread devastation at ground level may 
occur. At the current state of knowledge, it is about as likely to 
happen next week as in a randomly selected week a thousand years from 
now.
The Survey
    In an effort to gain better understanding of this hazard, NASA has 
been conducting a search of space near the Earth's orbit to understand 
the population of objects that could do significant damage to the 
planet should there be a collision. Commonly referred to as the 
``Spaceguard Survey'', NASA's Office of Space Science conducts this 
research effort on ``Near Earth Objects (NEOs)''--that is, asteroids 
and comets that come within an astronomically close distance, <50 
million kilometers of Earth. The objective of this survey is to detect, 
within a 10-year period, at least 90 percent of the NEOs that are 
greater than 1 kilometer in size and to predict their orbits into the 
future. The survey officially started in 1998 and to date, over 700 
objects of an estimated population of about 1100 have been discovered, 
so the effort is believed to now be over 70 percent complete and well 
on the way to meeting its objective by 2008.
    A few words of explanation on the parameters and limitations of the 
survey may be appropriate. The threshold of 1 kilometer in size was 
accepted for this survey because it is about the size asteroid that 
current research shows would border on having a devastating worldwide 
effect should an impact occur. Because of the orbital velocities 
involved, impact on Earth of an asteroid of this size would instantly 
release energies calculated to be equivalent to the detonation of 
almost a 100,000 megaton nuclear device, i.e., more than all the 
world's nuclear arsenals detonated at the same time. Not only would the 
continent or ocean where the impact occurs be utterly devastated, but 
the effects of the super-heated fragments of Earth's crust and water 
vapor thrown into the atmosphere and around the world would adversely 
affect the global weather for months to years after the event. Such an 
event could well disrupt human civilization anywhere from decades to a 
century after an impact.
    A goal of 90 percent completeness was adopted as a compromise 
driven between the level of resources that could be dedicated to this 
effort and the time period practical to conduct the survey at this 
level of technical capability. Currently, slightly over $4M per year is 
budgeted to the NEO Observation Program within the Solar System 
Exploration Division's Supporting Research and Analysis Program. This 
funds modest search efforts, typically using refurbished, ground-based 
telescopes of about 1-meter aperture and wide-field-of-view, coupled 
with digital imaging in order to cover significant portions of the sky 
each month. Presently, five NEO search projects are either wholly or 
largely funded with this level of resource, along with significant 
support to central processing of observations, orbit determination and 
analysis. These five search projects are:

------------------------------------------------------------------------
      Project Name              Institute         Principal Investigator
------------------------------------------------------------------------
Lincoln Near Earth Asteroid Research (LINEAR)
                         MIT/Lincoln Laboratory,  Dr. Grant Stokes
                          MA
Near Earth Asteroid Tracking (NEAT)
                         Jet Propulsion           Dr. Ray Bambery
                          Laboratory, CA
Lowell Observatory Near Earth Object Search
 (LONEOS)
                         Lowell Observatory, AZ   Dr. Edward Bowell
Catalina Sky Survey      LPL, University of       Mr. Steve Larson
                          Arizona
Spacewatch               LPL, University of       Dr. Robert McMillan
                          Arizona
------------------------------------------------------------------------

    Both the LINEAR and NEAT projects operate using optical telescope 
facilities owned and supported by research components of the U.S. Air 
Force. This represents that service's entire contribution to the search 
effort, but utilization and direction of these assets must be 
coordinated with the cognizant Air Force Material Command offices. The 
Spacewatch Project also receives some modest private funding.
    Ten years was considered a reasonable amount of time for this level 
of effort to bring the overall large asteroid population known to 90 
percent completeness. No level of effort could ever be assured of 
achieving absolute 100 percent completeness, because of the vast 
difficulty in searching all possible orbit regimes and sources for 
generation of new NEOs. It should also be understood that the NEO 
Observation Program is merely a science survey and does not have the 
resources to provide a ``leak-proof'' warning network for impact of any 
size natural object, large or small. Such a comprehensive network would 
require an order of magnitude increase in funding and could require the 
cooperative efforts of several government departments and agencies.
Progress of the Program
    The NEO Observation Program continues to make steady progress 
toward the goal of finding at least 90 percent of the large NEO 
population. As of the end of March 2004, 513 of the 750 known NEOs 
(including 49 Earth-approaching comets) determined to be larger than 1 
kilometer in size have been found by the program, of an estimated total 
population of about 1100. In addition, the program found 1862 of 2032 
known Near Earth Asteroids (NEAs) of smaller sizes. The MIT/Lincoln 
Labs-led LINEAR project continues to be the leading search team, having 
found 40 large NEOs in 2003 along with 196 smaller objects. Significant 
contributions continue to be made by JPL's NEAT team (10 large and 58 
smaller objects in the last year), Lowell Observatory's LONEOS project 
(10 and 44), and the University of Arizona's Spacewatch project (2 and 
54). The Lunar and Planetary Laboratory Catalina Sky Survey has gotten 
back on line in the last few months of the year after an imager 
upgrade, obtaining 8 discoveries, 2 of them larger than 1 km.
    The chart below summarizes the progress to date on finding the NEAs 
greater than 1 kilometer in size. A noticeable increase in the 
discovery rate occurs after the NEO Observation Program started in 
1998.
    Budget. The FY 2004 budget for this program is $4,062K, a 2.8 
percent increase to the previous year.

[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]


Current Survey Operations
    Detection. The NEO Observation Program wholly funds the operations 
of four search projects and partially funds another. Routine operation 
of these assets is highly automated, in order to maximize the sky 
coverage obtained each month. Ground-based telescopes can only 
effectively operate at night during the two to three weeks of the month 
opposite the full moon, due to the sky brightness it causes, and when 
weather (cloud cover) permits accessible clear sky. Telescope movement, 
pointing, and imaging operations are all computer controlled via pre-
scripted software routines to optimize sky coverage and therefore 
maximize object detections.
    The images taken each night are then post-processed to detect 
moving objects relative to the star background and obtain accurate 
measurements, called ``observations'', of any detected object's motion 
relative to the star background (a process called ``astrometrics''). A 
group of these observations, usually a set taken from three to five 
images of the same patch of sky at slightly different times each night, 
is called a ``track''. These show the relative motion of an object, 
which can then be analyzed with other observations of the same object 
to determine its orbit. These observation tracks are then formatted for 
bulk telecommunications to the Minor Planet Center. On a productive 
night, a search project may extract hundreds of observations on moving 
objects from its imaging data, most of which will be on Main Belt 
Asteroids and only a small fraction, perhaps one or two if lucky, will 
be determined to be NEOs. The search teams also routinely find comets 
in their collected images.
    The Minor Planet Center. All observations thought to be natural 
small bodies (asteroids, comets and now Kuiper Belt Objects in the 
outer Solar System) are sent to the Minor Planet Center (MPC), operated 
by the Smithsonian Astrophysical Observatory at Cambridge, 
Massachusetts, under the direction of Dr Brian Marsden. The MPC is 
internationally recognized and officially chartered by the 
International Astronomical Union to confirm the discovery of new 
objects in the Solar System and confer their official designations. A 
modest amount of NASA funding is sent to the MPC to support their work 
in confirming NEO detections.
    The MPC receives observations from around the world, with a 
significant percentage coming from an informal international network of 
amateur asteroid hunters. The orbital analyst at MPC attempts to 
correlate them with the positions of tens of thousands of already known 
objects. Failing that, the MPC will provisionally designate the 
observations as a possible new object, determine an ``initial'' orbit 
for it, and place it on a list for objects awaiting ``confirmation''. 
This list of provisional objects, along with their predicted current 
positions, is available via the MPC website for the community of 
observers to use in attempts to obtain additional ``follow-up'' 
observations to confirm the existence and orbit parameters of a new 
object.
    The observation processing at the MPC is highly automated, as it 
must be with a staff of only three to four analysts operating with a 
very limited budget. However, initial orbit determination often 
requires some analyst's massaging of the orbit fit to obtain the lowest 
residuals across what may be observations with some inherent errors. 
Because individual search sites can only do the roughest of orbit 
calculations based on their own limited data, the MPC is, in most 
cases, the first place where it will be known if a newly found object 
poses an impact hazard to the Earth. Often a family of possible orbits 
is initially obtained which must be narrowed with additional 
observations. For newly found NEOs, the MPC solicits additional 
observations from the community via a web-based ``NEO Confirmation 
Page'', and in the most critical cases, via phone calls to known 
observers in whatever part of the world is most likely to have the 
earliest accessibility to viewing the object.
    Follow-up Observations. Additional observations, either obtained by 
another observer later the same night or on a subsequent night, even by 
the same facility that first discovers an object, are essential to 
confirming the objects existence and developing a more accurate orbit 
for the object. For the most accurate orbit, it is best for the 
observations to be obtained several days to a week or more after the 
initial set in order to obtain a longer observed ``arc'' of the orbit 
and, therefore, a broader fit of observation data. However, for NEOs, 
the time allowed to elapse must be traded off between obtaining a 
broader arc and getting an orbit established before the object is lost, 
either because the initial orbit was too far in error, or, more likely, 
the object is so small that it simply cannot be seen after only a few 
days of its closest approach to Earth.
    The informal network of amateur astronomers does much of the 
follow-up observation work today. However, the search for NEOs is 
beginning to enter an era when the objects being detected are simply 
too faint to be seen by the equipment affordable to most amateurs. 
Therefore, in the future, search systems must ensure they have enough 
survey capacity available to do their own follow-up on new objects in a 
timely manner.
    High-accuracy Orbit Determination. The best orbit determination 
requires enough observations spread over a sufficient arc of the orbit 
to provide the best resolution of motion for the object and reduce the 
influence of subsets of data with may have some components of error. 
Again, getting the best results can be somewhat of an art form, but the 
best orbital modeling for this reside with the NEO Program Office 
established by NASA at the Jet Propulsion Laboratory in Pasadena, 
California, and managed by Dr. Donald Yeomans. This office also 
supports the orbit determination and navigation for NASA's 
interplanetary missions to asteroids, comets, and moons of other 
planets. Its NEO work is fully funded by NASA, and the high-accuracy 
orbit determination capability is nicely complementary to the MPC's 
observation processing and initial orbit determination abilities.
    The NEO Program Office is able to use its orbital modeling 
capability to predict the position of any known NEO up to 200 years 
into the future, taking into account all the known gravitational 
influences and orbital perturbations of the Sun, planets, and moons in 
the Solar System. This can be done with a very high degree of precision 
for asteroids that have been tracked for extended periods, particularly 
multiple orbits, or for which high-precision observations have been 
taken by planetary radar. High-precision radar observations can greatly 
reduce the position and motion errors for the subset of objects that 
come close enough to the Earth to allow its use.
    High-precision prediction of newly discovered NEO orbits allows 
them to be separated into those whose orbits will not be a collision 
hazard to Earth for the foreseeable future and those which are in 
orbits that pass close enough to Earth's that they may someday pose a 
hazard. These ``Potentially Hazardous Asteroids (PHAs)'' are about a 20 
percent subset of all NEOs found. Of course, known and unknown errors 
in the NEO's orbital parameters can propagate out to significant 
uncertainty in the position when predictions are done decades into the 
future. Therefore, periodic observation of known objects, especially 
those known to be in potentially hazardous orbits, must be done to 
update the last known position and reduce the orbit errors.
Low Probability, High Consequence Events on Short Timelines
    A central premise of the current survey effort is that in the 
relatively short 10-year period, the search teams would be able to find 
almost all asteroids of greater than 1 kilometer dimension that might 
pose a threat of impact--many years to multiple decades before any such 
event. It could perhaps even provide many centuries advanced notice, 
since this level of event is thought to happen only once or twice in a 
million years. Hypothetically, this would allow ample time to develop 
the techniques and technologies that may be required to deflect or 
mitigate a predicted disaster. But until the total population of these 
objects is known, there is always a chance that an object bound for a 
nearer term impact may be discovered, similar to the real-life scenario 
which unfolded when Comet Shoemaker-Levy 9 was discovered in March 1993 
inbound for a July 1994 impact on Jupiter.
    The results of a recent study by a Science Definition Team 
commissioned by NASA's Solar System Exploration Division show that it 
is entirely appropriate that we search for the larger NEOs first 
because, all factors considered, that is where the greatest risk for an 
undetected asteroid on an impact trajectory lies, principally due to 
the widespread devastation it would cause. It is orders of magnitude 
above what smaller, sub-kilometer sized impactors would produce. 
Completion of the current effort to find these large objects will do 
much to reduce the uncertain risk of which we have now become aware.
    But more frequent would be the discovery of a relatively small 
asteroid on a potential impact trajectory with Earth, as this occurs 
more often. Since the optical sensors used in the survey detect the 
brightness of the object against the sky background, which can only be 
approximately related to an asteroid's size based on assumed 
reflectivity of light, the search systems are as capable of finding 
smaller asteroids at closer range as larger objects much farther away. 
They are designed to detect 1 kilometer sized asteroids at least 50 
million kilometers distant but can also detect an asteroid a dozen 
meters in size within the Moon's distance from Earth.
    Operational experience with the current systems shows that for 
every 1-kilometer or greater sized asteroid found, there are three to 
four smaller sized asteroids also discovered. But the true ratio of 
smaller asteroids, say 100-meter or larger objects to 1-kilometer or 
larger objects, is thought to be closer to 100 to 1. Because of the 
limitations of the search systems, the discovery of smaller asteroids 
is in a significantly smaller volume about the Earth--an object one 
tenth the size of another must be about hundred times closer to be seen 
by the sensor, assuming equal reflectivity of their surfaces. If the 
sensor can detect a 1 kilometer sized asteroid at 50 million 
kilometers, it should theoretically also see a 100-meter asteroid at 
500,000 kilometers.
    However, at planetary relative orbital velocities, if the object is 
on collision course with the Earth, it may cover even this distance in 
less than one day. Thus the detection of a relatively small asteroid on 
a collision trajectory with Earth could also come with a relatively 
short reaction time. A 100 meter asteroid on direct collision with 
Earth could do significant damage at the surface as this is estimated 
to result in an approximately 50 megaton energy release at or perhaps 
slightly above the surface. This would result in much loss of life if 
the impact were in a populated area. It is therefore prudent that we 
begin to put in place some contingency plans, such as an internal NASA 
notification plan we are drafting, to deal with such a relatively 
unlikely but extremely high-consequence event.
    Again I thank you for the opportunity to appear and would be happy 
to respond to any questions.

    Senator Brownback. Thank you, gentlemen. I'm sorry that 
Astronaut Nelson had to leave, but he submitted a series of 
questions for the record that I would like to submit to you 
gentlemen if you could get back to him in a timely time, I 
would appreciate you doing that and I'll put that into the 
record.
    As you look at that, what are the chances of Earth being 
hit by a substantial near earth target? I put forward the 
chance is the same as being involved in an airliner crash. Is 
that an accurate assessment? Do you think that's inaccurate? Or 
where would you place it?
    Dr. Johnson. From the studies that we've had, yes, that is 
about the probability that is equivalent to about a million to 
one--a million--or one in 500,000 somewhere in that range.
    Senator Brownback. We're talking about a substantial size 
object. What would you categorize as a substantial size object 
to hit us in that chance range?
    Dr. Johnson. Anything that's large enough to make it 
through the atmosphere, anything larger than 80 meters or 200 
feet in size.
    Senator Brownback. I was looking at your chart and you're 
saying that we're catching right about 700, that we've got 
categorized and you've placed the estimated total at around 
1,100, is that correct?
    Dr. Johnson. Yes. That's based upon the distribution that 
we've seen to date. We've actually lowered that estimate 
through the course of the program by about 40 percent. We were 
thinking the overall population was about 2,000, but what we've 
seen so far, we think that population is somewhat less than the 
original estimates and it's about 1,100 plus or minus 100 or 
so, the large one kilometer size.
    Senator Brownback. OK, these are the large one kilometer 
size, right? And I thought you said there was 100 to one ratio 
of the large to the small.
    Dr. Johnson. Yes. We believe it's kind of a power law of 
the numbers. As you get smaller, you know, a 100 to one ratio 
of sizes----
    Senator Brownback. You're not worried about their impact on 
the Earth should they hit, the smaller ones. Is that correct?
    Dr. Johnson. No. We are worried about it. Until you get 
down to a size that Earth's atmosphere will dissipate, and 
that's down to about 50 meters, you have to worry about damage 
all the way to the surface of the Earth of anything that's 
larger than about 50 meters.
    Senator Brownback. OK. So what I hear you saying and you've 
made substantial progress on the one kilometer or larger----
    Dr. Johnson. Yes.
    Senator Brownback.--ones, but we're still somewhere--you 
think there's 1,100--you think there's 400 or so out there that 
we have not found yet.
    Dr. Johnson. Of the large ones, the ones that would do 
worldwide devastation if they were to hit.
    Senator Brownback. But you're at 100 to one times of others 
than that could do substantial damage. Depending upon their 
size and we don't have any idea where they are?
    Dr. Johnson. Right. The original charter of the NEO 
Observation Program was to find the large ones that would have 
worldwide global consequences, but there's kind of a big 
elephant out there. We're taking it a bite at a time.
    Senator Brownback. So if you've got one that's half a 
kilometer in size--let's say what kind of damage could that do? 
Do you have any estimates of what that would be?
    Dr. Johnson. Well, that devastation on the order of the 
continent if it were to hit on land, pretty much the continent 
that it hits would be affected. However, if it were to hit in 
the ocean the ocean wave that would be caused, the tsunami, 
would probably impact on both coasts. If it were hit in the 
Middle Atlantic, both the Eastern seaboard of the United States 
and the European seaboard would be affected by a large tsunami 
of several meters, if not a 100 meters in height.
    Senator Brownback. And we're not even tracking those yet?
    Dr. Johnson. No, we're not tracking those yet. We are 
finding them when they come close to Earth, come close enough 
to Earth for our sensors to see it, but we know that there are 
a lot more out there.
    Senator Brownback. So when you say we're finding them when 
they come close enough to Earth, how close and how much time do 
we have between when we're finding them now and when they would 
impact Earth?
    Dr. Johnson. Well, as I said, so far those that we've 
found, none of them are on impact trajectories. It all depends 
on what the orbit is. It could be as rapidly as a day or two if 
it's on a direct impact, or it could be decades or centuries 
into the future until the orbits intersect.
    Senator Brownback. Well, how much--you say we're finding 
virtually all of them now that are coming in close to the 
Earth. Did I understand or did I ask that correctly?
    Dr. Johnson. We're finding virtually all the large ones 
that come close enough.
    Senator Brownback. Kilometer or larger?
    Dr. Johnson. Yes.
    Senator Brownback. What about those that are a half a 
kilometer?
    Dr. Johnson. I would give you no guarantee on what the 
coverage is for those.
    Senator Brownback. Of what we're finding at all?
    Dr. Johnson. Right. What we're currently using are not 
designed to find the small ones.
    Senator Brownback. Are you comfortable with what we're 
doing to date on this topic?
    Dr. Johnson. As I said, it's a pretty big elephant and 
you've got to take it a chunk at a time. I'm comfortable that 
we are finding the large ones, but there is a hazard out there 
still of the small ones.
    Senator Brownback. It sounds like to me it's a large 
hazard.
    Dr. Johnson. Yes, it is.
    Senator Brownback. And that we're not going through that 
set at all? I mean, I understand that there are costs 
associated with this and there's user resources that you've got 
to do. I trying to assess what's the nature of the damage 
potential?
    Dr. Johnson. I think that's an accurate assessment. We are 
finding the ones that would have global consequence if they 
were to impact, but it's only serendipitously that we find the 
smaller ones that could still do significant damage if they 
were to impact.
    Senator Brownback. What's the likelihood, the odds of us 
being hit by a smaller object, say that's a half a kilometer in 
size. Do we have any projections on the odds of being hit by 
one of those in the next 100 years?
    Dr. Johnson. In the next 100 years, it'd be very, very 
small. Our estimates are that one 500 meters in size or so 
would impact maybe once in 100,000 years. Something like that. 
But we also believe that small ones, those on the order of 100 
meters or so, impact once every few hundred to a thousand 
years.
    Senator Brownback. What kind of damage could those cause?
    Dr. Johnson. The energy release from a 100 meter object 
that's of average density would be about 50 megatons at the 
surface, or slightly above the surface of the Earth. That's 
larger than any nuclear weapon that we have.
    Senator Brownback. So you're talking about a catastrophic 
event wherever it occurs?
    Dr. Johnson. The region that it impacts in, yes.
    Senator Brownback. And what are the odds of that taking 
place?
    Dr. Johnson. Well, if on the average it happens once in 
1,000 years that's your probability. Maybe once in 1,000 years.
    Senator Brownback. Do we know when the last time one of 
these hit the Earth was?
    Dr. Johnson. Well, close to that size was the Tunguska 
Event in 1908. That one was probably slightly smaller somewhere 
in the 70 meter range. Something like that.
    Senator Brownback. What was the impact of that event?
    Dr. Johnson. Well, it actually exploded above the Earth's 
surface probably at five to seven kilometers, but it still 
devastated several hundred square kilometers of forest in 
Siberia. The over pressure just blew the forest down and so if 
it were to hit in a populated area it would be like a nuclear 
device going off.
    Senator Brownback. And this is an item of 100 meters in 
size. Is that correct?
    Dr. Johnson. That's correct.
    Senator Brownback. And we don't have any idea of the 
quantity of those that are out there that might be on some 
orbital pattern toward the Earth?
    Dr. Johnson. We believe they're in the hundreds of 
thousands.
    Senator Brownback. Hundreds to thousands?
    Dr. Johnson. Hundreds of thousands.
    Senator Brownback. Hundreds of thousands?
    Dr. Johnson. Objects, yes.
    Senator Brownback. And that those hit the Earth you say 
once every how often?
    Dr. Johnson. Once every thousand years.
    Senator Brownback. Are we doing enough, Dr. Van Citters?
    Dr. Van Citters. I think we could do a lot more. I think 
that the study that NASA commissioned identified a very 
reasonable set of parameters for future searches to carry on 
from the one kilometer on down. We have a little more 
technology development to do in terms of large area detectors 
and so on, but the ideas that our community has presented to us 
and to Lindley's program and so on and how you might continue 
from here, I think are very credible.
    I think there's a fair amount of trade study that we need 
to do to look at how one might best carry out an extended 
search whether it's in one instrument or a series of 
instruments or if it's assigning parts of the search different 
instruments and so on, but I think we could do a better job as 
I indicated in things like the large Synoptic Survey Telescope 
will quite naturally in the way they operate, catalogue tens of 
thousands of these objects and provide the kind of completeness 
that the expert committee has put in front of us.
    Senator Brownback. These would be objects of much smaller 
in size than the one kilometer?
    Dr. Van Citters. Yes, this would be we--our sense of the 
estimates, and these are of course just estimates, would be 
that the surveys would be complete within--and it depends a 
little bit on how you do them, but it's somewhere between 7 
years and 20 years of operation, the surveys would be 90 
percent complete down to 140 meters, which is of course a 
substantial increase in our knowledge of the objects.
    Senator Brownback. Let me ask you on the other side of 
this, just the knowledge we could learn from these Near Earth 
Objects. We've got a Scientific American article I think we'll 
have some people testifying about, about using these as 
tugboats for information of hooking probes on them, of what we 
could gain from asteroids. Have either of you dealt with that 
side of this equation or thought?
    Dr. Johnson. Not too much. We do have studies going on what 
we call, ``characterization studies,'' to find out what these 
things are made of and that would help us to determine what 
kind of resources are present on these and so theoretically if 
there are resources there that are of benefit to either us on 
Earth or in the exploration of the solar system, one could 
think of mining operations going on on Near Earth Asteroids.
    Senator Brownback. What about using--that we put probes on 
to carry the probe out further into the galaxy.
    Dr. Johnson. Ones that are on the right kinds of orbits 
that do go out into the solar system, potentially that's an 
idea.
    Senator Brownback. Dr. Van Citters?
    Dr. Van Citters. There's certainly a lot of interest in our 
community and indeed in the research that we re funding, 
because these objects are--as you indicated in your opening 
remarks, left over from the formation of the solar system. And 
so as we catalogue more of them, look at their orbits, where 
they lie in the solar system, we get more spectroscopy to 
characterize what they're made of, whether they're binary in 
nature and so on, we have a very good probe of the very early 
days of our own solar system. And add to our knowledge of basic 
research in that area.
    I should say too that there are, I think, we concentrate on 
the astronomical aspects of this problem, there are other areas 
that I think are very valid areas of research that would be 
supported by other areas of the Foundation. And as we are 
talking this afternoon, it ran through my mind that we have a 
very active area, for instance, in mathematical sciences, 
looking at the propagation of uncertainty in very complex 
models.
    And as we go through a study like the one that NASA 
commissioned, the uncertainties in the prediction of what the 
population of the asteroids is, what they're made of, 
uncertainties in observation and so on, propagation of those 
into an analysis of the risk at the end which we must then use 
as a parameter to size systems and so on is a very active area 
of mathematical research and something that would apply there.
    Two, there's also the evaluation and the public perception 
of risk. You characterized the risk, or tried to draw the 
parallel between the risk of being struck by a large asteroid 
and riding in an airplane. There are certainly different 
perceptions among the populace of the risk of riding in an 
airplane versus the risk of riding in a car in certain cases. 
And I think the social sciences are extremely interested in how 
that sort of risk analysis and risk perception plays out, 
particularly in something like this, which is not something 
within our--perhaps should be, but not something within 
everyone s everyday thought process.
    Senator Brownback. That's very interesting, gentlemen, and 
I appreciate your work. How do you sleep at night, Dr. Johnson, 
with this knowledge?
    Dr. Johnson. I sleep very well at night. But it's not 
something I worry about on a daily basis, but over time, it's 
something we need to be concerned with.
    Senator Brownback. That's what it looks like to me. It's 
one of those things that we need to know the information for 
safety purposes first. Protection is the reason the initial 
Federal Government was created, was to provide for the security 
of the people. And so you're always out there searching, what's 
the security issue. And you could say, well, the odds are this 
or that, but if something happens, it's significant. So you 
really want to do everything you can.
    And then on the flipside, it seems like there's some real 
exploration and research that could be done if we knew more of 
just what all was out there. There's a security issue here 
which is of paramount concern. And then there's a curiosity/
research issue that seems like a significant benefit if we knew 
a lot more of what all was out there.
    Dr. Johnson. These objects are the building blocks of the 
planets. They're the building blocks of Earth. So the more we 
learn about these objects, the more that we will learn about 
the Earth.
    Senator Brownback. Gentlemen, thank you very much. I 
appreciate your coming in and I hope everybody listening in 
sleeps well tonight.
    We have a second panel. Dr. Grant Stokes, Associate Head of 
Aerospace Division at MIT in Massachusetts; Dr. Michael 
Griffin, Head of the Space Department at Johns Hopkins 
University, Applied Physics Lab; Mr. Rusty Schweickart, 
Chairman of the Board, B612 Foundation; and Dr. Ed Lu, 
President, and NASA Astronaut, of the B612 Foundation.
    Gentlemen, I appreciate very much your coming and joining 
in the panel and discussion today on Near Earth Objects. All of 
your written statements will be placed into the record. Dr. 
Stokes, we'll start with you and then we'll proceed down the 
list as I announced it.
    Welcome to the Committee. You might pull that microphone up 
kind of close to you. It's fairly directional.

 STATEMENT OF DR. GRANT H. STOKES, CHAIRMAN, NEAR EARTH OBJECT 
        SCIENCE DEFINITION TEAM, MIT LINCOLN LABORATORY

    Dr. Stokes. All right. Thank you, Mr. Chairman, for the 
opportunity to present to the Subcommittee information on NEOs 
this afternoon. I'm here to represent the findings of the Near 
Earth Object Science Definition Team, which I led recently for 
NASA. And you've heard a little bit from the previous folks 
about that.
    The team was tasked to address a series of specific 
questions intended to explore the technical possibilities of 
searching for asteroids smaller than the current one kilometer 
goal, and the efficacies of those searches. The study team 
which was composed broadly of experts through the community 
addressed the question by performing an exhaustive analysis 
along two parallel paths.
    First, the team established the current estimates of the 
Near Earth Object population, estimated the collision rates 
over time as functions of size, and then the damage expected 
from those types of collisions.
    Second, the team evaluated the technologies available to be 
built into systems intended to search for asteroids, and 
estimated their implementation costs and the effectiveness of 
discovering and cataloguing potentially dangerous asteroids.
    Combining that information from those two paths of analysis 
systems and strategies on a cost/benefit basis. The cost of 
investment in a search system balanced against the benefit of 
providing awareness of potential short or long term threats.
    The team specifically did not address issues related to 
mitigation approaches in the highly unlikely event that we find 
an object, a substantial object, on a collision course with 
Earth, but the view was that if one was coming, we certainly 
wanted to know.
    The team estimated the annual nominal average risk 
remaining in 2008, associated with an asteroid impact would be 
approximately 300 casualties per year, that's worldwide, plus 
the attendant property damage and destruction. That breaks down 
to about 17 percent of that risk is attributed to smaller 
objects doing regional damage for land impacts, about 53 
percent of that is due to water impacts and the tsunamis that 
ensue, and 30 percent of that risk is global climatic 
disruption caused by large impacts. So those are the physical 
objects left over, undiscovered by the Space Guard Survey in 
2008.
    Senator Brownback. You re saying 300 deaths per year?
    Dr. Stokes. That's the average rate. Now, remember, that's 
composed of events that happen over long intervals, but some of 
them can be quite destructive. That average risk is composed of 
devastating events that may occur only once over periods very 
long compared to the life of an individual.
    Senator Brownback. So if there's another like 1908 event 
that occurs in 2030, you re calculators add----
    Dr. Stokes. Right.
    Senator Brownback. The large number of casualties of that 
event, but you're calculating it over a period of time.
    Dr. Stokes. Correct.
    Senator Brownback. All right.
    Dr. Stokes. In any particular year, the most likely number 
of casualties due to an asteroid impact is zero. Now, in fact, 
over periods of millions of years, there have been extinction 
events like the dinosaurs 65 million years ago, which would 
essentially cause the loss of civilization. And that is some 
part of the average rate.
    The 300 casualties per year that I mention is the left over 
after we execute the current surveys. The actual yearly rate, 
much of which has already been taken care of by the surveys, 
would have been about 1,200 per year, if we started with no 
information.
    In addition, the team concluded that current technology 
offers asteroid detection and cataloguing capabilities several 
orders of magnitude better than presently operating systems. It 
is resources rather than technology that is the current 
limitation on NEO search performance. The team identified a 
variety of search system examples which, when operated over 
periods ranging from 7 to 20 years, would generate a catalogue. 
That catalogue would contain hundreds of thousands of asteroids 
and would be 90 percent complete for Near Earth Objects larger 
than 140 meters. Construction and operation of these systems to 
achieve the level of completeness is estimated by us to cost 
somewhere between $296 million and $397 million, that's in 
Fiscal Year 2003 dollars.
    All of those systems----
    Senator Brownback. Is that a total figure, or is that 
over----
    Dr. Stokes. That's a total figure including building the 
system and operating it to that level of completeness, which 
would take 7 to 20 years, depending on how aggressive--if one 
is in a hurry, one should look at space-based systems. If one 
wants to take longer, it can be done from the ground.
    All of those systems that I mentioned have a favorable 
cost/benefit pay back when measured in the unknown risk 
eliminated by the dollars invested in the asteroid search 
system. Based on those findings, the team recommended three 
things for NASA.
    First, we recommended that future goals related to search 
for potential Earth-impacting objects should be stated 
explicitly in terms if the statistical risk eliminated or 
characterized, and should be firmly based in a cost/benefit 
analysis.
    Second, we recommend that NASA develop and operate a NEO 
search program with the goal of discovering and cataloguing the 
potentially hazardous population sufficient to eliminate 90 
percent of the risk due to the sub-kilometer objects. That 
would imply 90 percent completeness in the catalogue to the 140 
meter level.
    Third, to get things rolling, we suggest that NASA release 
an announcement of opportunity, or an AO, to allow system 
implementers to recommend a specific approach to satisfy the 
goal stated in recommendation two, which we are sure is 
technically possible.
    Thank you and I would be happy to respond to questions.
    [The prepared statement of Dr. Stokes follows:]

Prepared Statement of Dr. Grant H. Stokes, Chairman, Near-Earth Object 
            Science Definition Team, MIT Lincoln Laboratory
    Thank you, Mr. Chairman, for the opportunity to present to the 
subcommittee information on the subject of Near Earth Objects. In 
recent years, there has been an increasing appreciation for the hazards 
posed by near-Earth objects (NEOs), those asteroids and periodic comets 
(both active and inactive) whose motions can bring them into the 
Earth's neighborhood. In August of 2002, NASA chartered a Science 
Definition Team to study the feasibility of extending the search for 
near-Earth objects to smaller limiting diameters. The formation of the 
team was motivated by the good progress being made toward achieving the 
so-called Spaceguard goal of discovering 90 percent of all near-Earth 
objects (NEOs) with diameters greater than 1 km by the end of 2008. 
This raised the question of what, if anything should be done with 
respect to the much more numerous smaller, but still potentially 
dangerous, objects. The team was tasked with providing recommendations 
to NASA as well as the answers to the following 7 specific questions:

  1.  What are the smallest objects for which the search should be 
        optimized?

  2.  Should comets be included in any way in the survey?

  3.  What is technically possible?

  4.  How would the expanded search be done?

  5.  What would it cost?

  6.  How long would the search take?

  7.  Is there a transition size above which one catalogs all the 
        objects, and below which the design is simply to provide 
        warning?
Team Membership
    The Science Definition Team, which I lead, was composed of experts 
in the fields of asteroid and comet search, including the Principal 
Investigators of two major asteroid search efforts, experts in orbital 
dynamics, NEO population estimation, ground-based and space-based 
astronomical optical systems and the manager of the NASA NEO Program 
Office. In addition, the Department of Defense (DOD) community provided 
members to explore potential synergy with military technology or 
applications. The Team members are listed in the following table along 
with their institutions.

 
 
 
Dr. Grant H. Stokes (Chair)      MIT Lincoln Laboratory
Dr. Donald K. Yeomans (Vice-     Jet Propulsion Laboratory/Caltech
 Chair)
Dr. William F. Bottke, Jr.       Southwest Research Institute
Dr. Steven R. Chesley            Jet Propulsion Laboratory/Caltech
Jenifer B. Evans                 MIT Lincoln Laboratory
Dr. Robert E. Gold               Johns Hopkins University, Applied
                                  Physics Laboratory
Dr. Alan W. Harris               Space Science Institute
Dr. David Jewitt                 University of Hawaii
Col. T.S. Kelso                  USAF/AFSPC
Dr. Robert S. McMillan           Spacewatch, University of Arizona
Dr. Timothy B. Spahr             Smithsonian Astrophysical Observatory
Dr./Brig. Gen. S. Peter Worden   USAF/SMC
 
Ex Officio Members
Dr. Thomas H. Morgan             NASA Headquarters
Lt. Col. Lindley N. Johnson      NASA Headquarters
 (USAF, ret.)
 
Team Support
Don E. Avery                     NASA Langley Research Center
Sherry L. Pervan                 SAIC
Michael S. Copeland              SAIC
Dr. Monica M. Doyle              SAIC
 

Analysis Process
    The Team approached the task using a cost/benefit methodology 
whereby the following analysis processes were completed:
    Population estimation--An estimate of the population of near-Earth 
objects (NEOs), including their sizes, albedos and orbit distributions, 
was generated using the best methods in the current literature. We 
estimate a population of about 1100 near-Earth objects larger than 1 
km, leading to an impact frequency of about one in half a million 
years. To the lower limit of an object's atmospheric penetration 
(between 50 and 100 m diameter), we estimate about half a million NEOs, 
with an impact frequency of about one in a thousand years.
    Collision hazard--The damage and casualties resulting from a 
collision with members of the hazardous population were estimated, 
including direct damage from land impact, as well as the amplification 
of damage caused by tsunami and global effects. The capture cross-
section of the Earth was then used to estimate a collision rate and 
thus a yearly average hazard from NEO collisions as a function of their 
diameter. We find that damage from smaller land impacts below the 
threshold for global climatic effects is peaked at sizes on the scale 
of the Tunguska air blast event of 1908 (50-100 m diameter). For the 
local damage due to ocean impacts (and the associated tsunami), the 
damage reaches a maximum for impacts from objects at about 200 m in 
diameter; smaller ones do not reach the surface at cosmic speed and 
energy.
    Search technology--Broad ranges of technology and search systems 
were evaluated to determine their effectiveness when used to search 
large areas of the sky for hazardous objects. These systems include 
ground-based and space-based optical and infrared systems across the 
currently credible range of optics and detector sizes. Telescope 
apertures of 1, 2, 4, and 8 meters were considered for ground-based 
search systems along with space-based telescopes of 0.5, 1, and 2 meter 
apertures. Various geographic placements of ground-based systems were 
studied, as were space-based telescopes in low-Earth orbit (LEO) and in 
solar obits at the Lagrange point beyond Earth and at a point that 
trailed the planet Venus.
    Search simulation--A detailed simulation was conducted for each 
candidate search system, and for combinations of search systems working 
together, to determine the effectiveness of the various approaches in 
cataloging members of the hazardous object population. The simulations 
were accomplished by using a NEO survey simulator derived from a 
heritage within the DOD, which takes into account a broad range of 
``real-world'' effects that affect the productivity of search systems, 
such as weather, sky brightness, zodiacal background, etc.
    Search system cost--The cost of building and operating the search 
systems described herein was estimated by a cost team from SAIC. The 
cost team employed existing and accepted NASA models to develop the 
costs for space-based systems. They developed the ground-based system 
cost estimates by analogy with existing systems.
    Cost/benefit analysis--The cost of constructing and operating 
potential survey systems was compared with the benefit of reducing the 
risk of an unanticipated object collision by generating a catalog of 
potentially hazardous objects (PHOs). PHOs, a subset of the near-Earth 
objects, closely approach Earth's orbit to within 0.05 AU (7.5 million 
kilometers). PHO collisions capable of causing damage occur 
infrequently, but the threat is large enough that, when averaged over 
time, the anticipated yearly average of impact-produced damage is 
significant. Thus, while developing a catalog of all the potentially 
hazardous objects does not actually eliminate the hazard of impact, it 
does provide a clear risk reduction benefit by providing awareness of 
potential short-and long-term threats. The nominal yearly average 
remaining, or residual, risk in 2008 associated with PHO impact is 
estimated by the Team to be approximately 300 casualties worldwide, 
plus the attendant property damage and destruction. About 17 percent of 
the risk is attributed to regional damage from smaller land impacts, 53 
percent to water impacts and the ensuing tsunamis, and 30 percent to 
the risk of global climatic disruption caused by large impacts, i.e., 
the risk that is expected to remain after the completion of the current 
Spaceguard effort in 2008. For land impacts and all impacts causing 
global effects, the consequences are in terms of casualties, whereas 
for sub-kilometer PHOs causing tsunamis, the ``casualties'' are a proxy 
for property damage. According to the cost/benefit assessment done for 
this report, the benefits associated with eliminating these risks 
justify substantial investment in PHO search systems.
PHO Search Goals and Feasibility
    The Team evaluated the capability and performance of a large number 
of ground-based and space-based sensor systems in the context of the 
cost/benefit analysis. Based on this analysis, the Team recommends that 
the next generation search system be constructed to eliminate 90 
percent of the risk posed by collisions with sub-kilometer diameter 
PHOs. Such a system would also eliminate essentially all of the global 
risk remaining after the Spaceguard efforts are complete in 2008. The 
implementation of this recommendation will result in a substantial 
reduction in risk to a total of less than 30 casualties per year plus 
attendant property damage and destruction. A number of search system 
approaches identified by the Team could be employed to reach this 
recommended goal, all of which have highly favorable cost/benefit 
characteristics. The final choice of sensors will depend on factors 
such as the time allotted to accomplish the search and the available 
investment.
Answers to Questions Stated in Team Charter
    What are the smallest objects for which the search should be 
optimized? The Team recommends that the search system be constructed to 
produce a catalog that is 90 percent complete for potentially hazardous 
objects (PHOs) larger than 140 meters.
    Should comets be included in any way in the survey? The Team's 
analysis indicates that the frequency with which long-period comets (of 
any size) closely approach the Earth is roughly one-hundredth the 
frequency with which asteroids closely approach the Earth and that the 
fraction of the total risk represented by comets is approximately 1 
percent. The relatively small risk fraction, combined with the 
difficulty of generating a catalog of comets, leads the Team to the 
conclusion that, at least for the next generation of NEO surveys, the 
limited resources available for near-Earth object searches would be 
better spent on finding and cataloging Earth-threatening near-Earth 
asteroids and short-period comets. A NEO search system would naturally 
provide an advance warning of at least months for most threatening 
long-period comets.
    What is technically possible? Current technology offers asteroid 
detection and cataloging capabilities several orders of magnitude 
better than the presently operating systems. NEO search performance is 
generally not driven by technology, but rather resources. This report 
outlines a variety of search system examples, spanning a factor of 
about 100 in search discovery rate, all of which are possible using 
current technology. Some of these systems, when operated over a period 
of 7-20 years, would generate a catalog that is 90 percent complete for 
NEOs larger than 140 meters.
    How would the expanded search be done? From a cost/benefit point-
of-view, there are a number of attractive options for executing an 
expanded search that would vastly reduce the risk posed by potentially 
hazardous object impacts. The Team identified a series of specific 
ground-based, space-based and mixed ground-and space-based systems that 
could accomplish the next generation search. The choice of specific 
systems will depend on the time allowed for the search and the 
resources available.
    What would it cost? For a search period no longer than 20 years, 
the Team identified several systems that would eliminate, at varying 
rates, 90 percent of the risk for sub-kilometer NEOs, with costs 
ranging between $236 million and $397 million. All of these systems 
have risk reduction benefits which greatly exceed the costs of system 
acquisition and operation.
    How long would the search take? A period of 7-20 years is 
sufficient to generate a catalog 90 percent complete to 140-meter 
diameter, which will eliminate 90 percent of the risk for sub-kilometer 
NEOs. The specific interval depends on the choice of search technology 
and the investment allocated, as shown in the figure below.
    The cost of various space-based and ground-based search systems are 
plotted against the number of search years required to reduce by 90 
percent the sub-global risk from impacts by sub-kilometer sized 
objects.


[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]



    The cost of various space-based and ground-based search systems are 
plotted against the number of search years required to reduce by 90 
percent the sub-global risk from impacts by sub-kilometer objects.

    Is there a transition size above which one catalogs all the 
objects, and below which the design is simply to provide warning? The 
Team concluded that, given sufficient time and resources, a search 
system could be constructed to completely catalog hazardous objects 
with sizes down to the limit where air blasts would be expected (about 
50 meters in diameter). Below this limit, there is relatively little 
direct damage caused by the object. Over the 7-20 year interval 
(starting in 2008) during which the next generation search would be 
undertaken, the Team suggests that cataloging is the preferred approach 
down to approximately the 140-meter diameter level and that the search 
systems would naturally provide an impact warning of 60-90 percent for 
objects as small as those capable of producing significant air blasts.
Science Definition Team Recommendations
    The Team makes three specific recommendations to NASA as a result 
of the analysis effort:

    Recommendation 1--Future goals related to searching for potential 
Earth-impacting objects should be stated explicitly in terms of the 
statistical risk eliminated (or characterized) and should be firmly 
based on cost/benefit analyses.
    This recommendation recognizes that searching for potential Earth 
impacting objects is of interest primarily to eliminate the statistical 
risk associated with the hazard of impacts. The ``average'' rate of 
destruction due to impacts is large enough to be of great concern; 
however, the event rate is low. Thus, a search to determine if there 
are potentially hazardous objects (PHOs) likely to impact the Earth 
within the next few hundred years is prudent. Such a search should be 
executed in a way that eliminates the maximum amount of statistical 
risk per dollar of investment.
    Recommendation 2--Develop and operate a NEO search program with the 
goal of discovering and cataloging the potentially hazardous population 
sufficiently well to eliminate 90 percent of the risk due to sub-
kilometer objects.
    The above goal is sufficient to reduce the average casualty rate 
from about 300 per year to less than 30 per year. Any such search would 
find essentially all of the larger objects remaining undiscovered after 
2008, thus eliminating the global risk from these larger objects. Over 
a period of 7-20 years, there are a number of system approaches that 
are capable of meeting this search metric with quite good cost/benefit 
ratios.
    Recommendation 3--Release a NASA Announcement of Opportunity (AO) 
to allow system implementers to recommend a specific approach to 
satisfy the goal stated in Recommendation 2.
    Based upon our analysis, the Team is convinced that there are a 
number of credible, current technology/system approaches that can 
satisfy the goal stated in Recommendation 2. The various approaches 
will have different characteristics with respect to the expense and 
time required to meet the goal. The Team relied on engineering judgment 
and system simulations to assess the expected capabilities of the 
various systems and approaches considered. While the Team considers the 
analysis results to be well grounded by current operational experience, 
and thus, a reasonable estimate of expected performance, the Team did 
not conduct analysis at the detailed system design level for any of the 
systems considered. The next natural step in the process of considering 
a follow-on to the current Spaceguard program would be to issue a NASA 
Announcement of Opportunity (AO) as a vehicle for collecting search 
system estimates of cost, schedule and the most effective approaches 
for satisfying the recommended goal. The AO should be specific with 
respect to NASA's position on the trade between cost and time to 
completion of the goal.
    The complete Science Definition Team Report may be accessed online 
at: http://neo.jpl.nasa.gov/neo/neoreport030825.pdf
    I thank you for the opportunity to appear and would be happy to 
respond to any questions.

    Senator Brownback. Thank you very much. Dr. Griffin.

STATEMENT OF MICHAEL D. GRIFFIN, HEAD OF THE SPACE DEPARTMENT, 
              APPLIED PHYSICS LAB, JOHNS HOPKINS 
                           UNIVERSITY

    Dr. Griffin. Thank you, Senator Brownback. I am here this 
afternoon, representing the Johns Hopkins Applied Physics 
Laboratory, which is so far the only laboratory which has 
carried out the mission of visiting a Near Earth Object with a 
robotic spacecraft.
    Thank you for providing me with this opportunity to comment 
on the greatest natural threat to the long-term survivability 
of mankind, which is an asteroid impact with the Earth.
    Throughout its history, Earth has been continuously 
bombarded by objects ranging in size from dust particles to 
asteroids or comets greater than 10 kilometers in diameter. 
You've heard that although the probability of the Earth being 
hit by a large object in this century is low, the effects of 
such an impact are so catastrophic that it is essential to 
prepare a defense against such an occurrence.
    The first step in that defense is a system to identify and 
catalogue all potential impacters above the threshold of 
significant damage, approximately 100 meters in diameter. 
Later, the remainder of a comprehensive Earth protection system 
could be assembled so that it would be ready to deflect a 
potential impacter shortly after it is identified.
    NEOs also represent a tremendous opportunity in the context 
of the President's exploration initiative. They are potential 
suppliers of resources for future manned space exploration, but 
in order to use these resources a much more detailed knowledge 
of their composition and physical characteristics will be 
required before the technologies to produce fuels or 
construction materials from Near Earth Objects can be 
developed.
    In 1998, NASA embraced the goal, as you've heard, of 
finding and cataloguing within 10 years 90 percent of all the 
Near Earth Objects with diameters greater than 1 kilometer. It 
is estimated that on the order of a thousand such objects 
exist. Population counts show, however, that there could likely 
be 150,000 Near Earth Objects larger than 100 meters, the 
threshold of significant damage on Earth.
    For reference, the Tunguska Event in Siberia in 1908 
destroyed an area 50 kilometers in diameter and is believed to 
have been caused by an impacter on the order of 50 meters in 
diameter.
    Again, you have already heard that the average--at the 
average speed of these objects, the energy released by the 
impact of 100 meter Near Earth Object is about equivalent to 
that of a 50 megaton bomb.
    The frequency of impacts over the last century can be 
estimated by noting the Tunguska Event in 1908, the Sikhote-
Alin Event in Siberia about 270 miles northeast of Vladivostok 
in February 1947, and the several recently identified objects 
that have had very near misses with the Earth.
    All this evidence confirms that impacts with the ability to 
wipe out a large metropolitan area can be expected within the 
next 100 years. It is also worth noting that within living--or 
at least recent memory, there is a 12 mile wide crater under 
the sea floor near the island of New Zealand, the impact of 
which lives on in Maori legends in the area. The impact is 
estimated to have occurred in the 1700s. These are not terribly 
infrequent events on human time scales.
    It is estimated that a 30 year advance warning would be 
required to have a reasonable assurance of deflecting a Near 
Earth Object from a collision with the Earth. If a future 
impacter were identified today, the time to explore the 
characteristics of the object, to develop a deflection system, 
deliver it to the NEO, and apply the deflection early enough to 
prevent an impact requires about a three decade lead time from 
the initial discovery.
    An overall Earth protection system must have three 
components. A search system is needed to identify any potential 
impacters, a series of detailed investigation missions are 
needed to understand the structure, composition, rotational 
state, and other physical properties of the impacter. And 
finally, deflection technologies are needed to change the speed 
of the object so that it will not impact Earth.
    At the current rate of discovery, the group of 
observatories that are finding and cataloguing Near Earth 
Objects will come close to achieving their goal of identifying 
90 percent of the greater than 1 kilometer diameter objects by 
2008. More than 50 percent of the population has already been 
discovered.
    The very large number of undiscovered, small to modest 
sized objects, the greater than 100 meters that I spoke of, 
represents the greatest remaining threat to regional safety not 
currently being addressed.
    A NASA Near Earth Object Science Definition Team recently 
examined the requirements for extending this search to smaller 
diameters and showed that a system to accomplish the discovery 
and cataloguing of 90 percent of these objects within 10 years 
could be accomplished with a single discovery class spacecraft 
in a heliocentric orbit, about seven-tenths of an AU out from 
the sun, or about at the orbit of Venus, relative to the sun. 
This modestly priced system could be constructed and launched 
in 4 to 5 years.
    My time is running out, and so I will conclude that in 
summary, the threat to life on Earth from Near Earth Objects is 
real, even though the likelihood of a severe impact during the 
next few years is low. The space exploitation opportunities of 
these objects are equally real. The most important thing needed 
at this time is an improved search system for smaller objects. 
Recent studies have shown that a search spacecraft can 
catalogue 90 percent of the remaining objects within 10 years 
and can be launched within the next 4 or 5 years.
    Thank you very much, and I'm ready to take any questions 
you may have.
    [The prepared statement of Dr. Griffin follows:]

Prepared Statement of Michael D. Griffin, Head of the Space Department, 
             Applied Physics Lab, Johns Hopkins University
    Mister Chairman and members of the subcommittee, thank you for 
giving me this opportunity to comment on the greatest natural threat to 
the long-term survivability of mankind, an asteroid impact with the 
Earth. Throughout its history, the Earth has continuously been 
bombarded by objects ranging in size from dust particles to comets or 
asteroids greater than 10 km in diameter. Although the probability of 
the Earth being hit by a large object in this century is low, the 
effects of an impact are so catastrophic that it is essential to 
prepare a defense against such an occurrence. The first step in that 
defense is a system to identify and catalog all potential impactors 
above the threshold of significant damage, approximately 100 meters in 
diameter. Later, the remainder of a comprehensive Earth-protection 
system could be assembled so that it would be ready to deflect a 
potential impactor shortly after it is identified.
    In 1998, NASA embraced the goal of finding and cataloging, within 
10 years, 90 percent of all near-Earth objects (NEOs) with diameters 
greater than 1 km. Impacts by objects of this size and larger could 
result in worldwide damage, and the possible elimination of the human 
race. The current system is not sufficient to catalog the population of 
smaller NEOs. While there are thought to be nearly a thousand objects 
with diameters greater than 1 km, there are a great many smaller NEOs 
that could devastate a region or local area. The exact NEO size 
distribution is not known; however a good current estimate is that 
there are more than 5 times as many objects with diameters greater than 
1/2 km than there are with diameters greater than 1 km. This 
multiplication of numbers for smaller diameters continues for all sizes 
at least down to those just large enough to make it through the 
atmosphere. Thus, if there are about 700 NEOs of 1 km or greater, there 
are more than 150,000 NEOs with diameters greater than 100 m. The 
Tunguska event in Siberia in 1908 destroyed an area 50 km in diameter 
and is believed to have been caused by an impactor less than 50 m in 
diameter.
    The average speed of objects colliding with Earth is about 20 km/s 
(about 45,000 miles per hour). At these speeds the energy of impact is 
44 times the explosive power of the same mass of TNT. Thus, the energy 
released by the impact of a 100 m object is about equivalent to a 50 
megaton bomb. The impacts at Tunguska in 1908, Sikhote-Alin (about 270 
miles northeast of Vladivostok) in February 1947, and the recently 
identified objects that have had near misses with Earth, all show us 
that impacts with the ability to wipe a large metropolitan area can be 
expected during the next 100 years.
    A great deal has been learned about the nature of the threat in the 
last decade. It is vital to understand the characteristics of NEOs to 
know how to defend against a potential impactor. An improved 
theoretical understanding of the population of NEOs has clarified their 
evolution through interactions with the planets of our solar system. It 
has helped us understand their numbers and their distribution in the 
different classes of orbits. On the practical side, the progress of 
several space missions has greatly improved our understanding of the 
physical and chemical characteristics of these objects. A great deal 
still needs to be done since only a handful of these objects have been 
observed from sufficiently close distances to see their surface 
structure, and only one asteroid has been orbited. The Near Earth 
Asteroid Rendezvous (NEAR) mission orbited and landed on 433-Eros and 
was able to get the first estimates of the internal structure and 
composition of a NEO. However, there is still a great deal more that 
will have to be known about an object if it becomes necessary to 
deflect it from a collision course with Earth.
Opportunities
    In addition to the threat that NEOs represent, they are also 
potential suppliers of resources for future manned space exploration. 
In order to use these resources, a much more detailed knowledge of 
their composition and physical characteristics will be required before 
the technologies to produce fuels or construction materials from NEOs 
can be developed.
Current and Future Technologies for Earth Protection
    It is estimated that a 30-year advance warning would be required to 
have a reasonable assurance of deflecting a NEO from a collision with 
Earth. Thus, if a future impactor were identified today, the time to 
explore the characteristics of the NEO, develop a deflection system, 
deliver it to the NEO, and apply the deflection early enough to prevent 
an impact, requires about a 3-decade lead time.
    The deflection technologies available today, which are chemical 
rockets and nuclear weapons, both have limited abilities to slow down 
or speed up an asteroid. A 100 m object has a mass of the order of 1 
million tons, and a 1 km object has a mass of the order of 1 billion 
tons. To prevent an object from colliding with Earth, it must be sped 
up or slowed down by about 7 cm/s (about \1/6\ of an mile per hour) 
divided by the number of years in advance that the change is applied. 
The fuel that can be contained in a medium-sized scientific spacecraft 
could successfully deflect a 100 m body if it were pushed about 15 
years in advance. The Space Shuttle's main engines and the fuel 
contained in the large external tank could successfully deflect a 1 km 
diameter object if it were applied about 20 years in advance. Nuclear 
weapons carry much greater impulse for their mass. However, they 
deliver that impulse so quickly that they are more likely to break up 
the body than to deflect it. Because NEOs are in their own orbits 
around the Sun, the pieces of a disrupted object will tend to come 
together one half of an orbital period later. Therefore, the successful 
use of nuclear weapons for deflection will require the development of 
techniques for slowing the delivery of the impulse to the NEO and will 
probably also require many small weapons to be used to deflect a single 
NEO.
    The orbital mechanics required to approach a potential impactor 
also require it to be identified early. It may take 5 years or more for 
any deflector mission to rendezvous with a NEO in an arbitrary Earth-
crossing orbit.
What Remains to be Done
    An overall Earth protection system must have three components. 
First, a search system is needed to identify any potential NEO 
impactors. Second, a series of detailed investigation missions are 
needed to understand the structure, composition, rotational state, and 
other physical properties of potential impactors. And finally, 
deflection technologies are needed to change the speed of a NEO to 
ensure that it will not impact Earth.
Search systems
    The United States and other countries around the world have 
concentrated on the first part of the Earth-protection system. At the 
current rate of discovery, the group of observatories that are finding 
and cataloging NEOs will come close to achieving their goal of 
identifying 90 percent of the greater than 1-km diameter NEO population 
by 2008. More than 50 percent of the expected population has already 
been discovered and discoveries continue to be made each month. While 
this effort will retire most of the risk of a global catastrophe, the 
size distribution of NEOs shows us that there are a great many more 
small objects than larger ones. Their numbers increase by a factor of 
about 220 for a diameter that is reduced by a factor of 10. This very 
large number of small-to-modest sized objects represents the greatest 
remaining threat to regional safety that is not being addressed. The 
equipment used by current NEO surveys is sized to find the largest 
objects. Some sub-kilometer objects are found serendipitously; however, 
these telescope systems are not optimized to find the smaller objects.
    A NASA NEO Science Definition Team recently examined the 
requirements for extending the NEO search to smaller diameters and 
showed that a system to accomplish the discovery and cataloging of 90 
percent of all NEO greater than 100 m diameter within 10 years could be 
accomplished with a single Discovery-class spacecraft in a heliocentric 
orbit at about 0.7 AU. This modestly priced system (the Discovery class 
is about $300 million full mission cost) could be constructed and put 
on-station in four to five years.
Detailed Examination of NEOs
    Several space missions that are contributing to the detailed 
investigations of NEOs and comets have been launched and others are 
currently in development. As stated above, the NEAR mission provided 
the first detailed information on the mass, shape, structure, and 
composition of an asteroid. However, we know from ground-based 
spectroscopic data that there is a great deal of variability among 
these objects.
    The Giotto and Deep Space 1 missions took close images of comets 
Halley and Borelli. The Stardust mission will be returning with dust 
particles from comet Wild 2 in January of 2006. The Deep Impact mission 
will create a crater in comet Tempel 1 to learn about the internal 
composition of comets. And the DAWN mission will examine the 
composition of asteroids 1 Ceres and 4 Vesta, two of the largest 
planetoids in the solar system. These missions are making steady 
progress in our understanding of the formation of the solar system and 
the characteristics of the small bodies within it. Continuation of this 
series of investigations is vital to our future ability to deal with 
the threat and opportunities of NEOs.
Deflection Technologies
    While there has been a great deal of theoretical examination of 
deflection techniques, no practical systems exist at this time. As the 
search systems and detailed examination missions progress, it is 
important to continue the development of deflection system technologies 
so that a full Earth-protection system could be deployed rapidly if a 
future impactor is discovered by the search systems.
Summary
    The threat to life on Earth from NEOs is real even though the 
likelihood of a severe impact during the next few years is low. The 
most important thing that is needed in order to deal with this risk is 
an improved search system. Recent studies have shown that a search 
spacecraft that can catalog 90 percent of the remaining NEOs larger 
than 100 m in diameter over 10 years of operation can be launched 
within 4 or 5 years at the cost of a NASA Discovery-class mission. In 
addition, the pace of mission developments for detailed examination of 
small solar system bodies should continue undiminished. This is clearly 
summarized by the cartoon below, originally published in New Yorker 
magazine in 1998.

[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]




                           Witness Biography
    Michael D. Griffin is Space Department Head, Johns Hopkins 
University Applied Physics Laboratory.
    Prior to joining APL, Mike served in a variety of executive 
positions with industry, including: President and Chief Operating 
Officer of In-Q-Tel, Inc., CEO of the Magellan Systems Division of 
Orbital Sciences Corporation, General Manager of Orbital's Space 
Systems Group, and Executive Vice President and Chief Technical Officer 
at Orbital. He has previously served as both the Chief Engineer and the 
Associate Administrator for Exploration at NASA, and as the Deputy for 
Technology of the Strategic Defense Initiative Organization.
    Before joining SDIO in an executive capacity, Mike played a key 
role in conceiving and directing several ``first of a kind'' space 
tests in support of strategic defense research, development, and flight 
testing. These included the first space-to-space intercept of a 
ballistic missile in powered flight, the first broad-spectrum 
spaceborne reconnaissance of targets and decoys in midcourse flight, 
and the first space-to-ground reconnaissance of ballistic missiles 
during the boost phase.
    Mike holds seven degrees in the fields of Physics, Electrical 
Engineering, Aerospace Engineering, Civil Engineering, and Business 
Administration, has been an Adjunct Professor at the George Washington 
University, the Johns Hopkins University, and the University of 
Maryland, and is the author of over two dozen technical papers and the 
textbook Space Vehicle Design. He is a recipient of the NASA 
Exceptional Achievement Medal, the AIAA Space Systems Medal, the DOD 
Distinguished Public Service Medal, and is a Fellow of the AIAA and the 
AAS. Mike is a Registered Professional Engineer in Maryland and 
California, and a Certified Flight Instructor with instrument and 
multiengine ratings.

    Senator Brownback. Dr. Griffin, just a couple real quick. 
That's the best way it's felt within the scientific community 
to do this, is to put a space-based observatory of sorts in an 
orbit out and around, to be able to categorize----
    Dr. Griffin. I wouldn't--that is one way. I wouldn't want 
to go so far as to say that the scientific community would 
regard it as the best way. The task can equally well be 
accomplished with a series or a set of ground-based telescopes 
spread as widely as possible on the Earth.
    And indeed, I believe NASA is open to both possibilities 
through the announcement of opportunity to which the previous 
witness alluded. So either ground-based--either several ground-
based observatories or a single space-based observatory could 
probably accomplish the same job.
    Senator Brownback. And what about the exploration 
opportunity and the research opportunity. What do you see as 
the biggest things we can learn from NEOs?
    Dr. Griffin. Well, I am an engineer by profession, and not 
a scientist. So my primary interest in Near Earth Objects would 
be for the exploration, exploitation, and development of a 
spacefaring infrastructure.
    Many Near Earth Objects will be found to be of the class of 
so-called carbonaceous chondrites from which volatile material, 
to include water, can likely be extracted. A small fraction of 
them, 1 or 2 percent, a few percent, will have heavy useful 
metals. Others will be merely rock and stone.
    But all of those together can provide construction 
materials, possibly fuel supplies. And those materials do not 
have to be lifted out of the gravity well of this planet or any 
other.
    This is a pursuit which should occupy us in the coming 
decades of space exploration. It will not be the first thing 
that we do, but it should be allowed to be the last thing we 
think of.
    Senator Brownback. Mr. Schweickart. Good to have you here.
    Mr. Schweickart. Thank you, sir. With your permission, I'd 
like to defer to Mr. Lu first, sir. Sequences would be better 
that way.
    The Chairman. That'll be just fine. Dr. Lu.

STATEMENT OF DR. EDWARD LU, NASA ASTRONAUT AND PRESIDENT, B612 
                           FOUNDATION

    Dr. Lu. Thank you for the opportunity to discuss a bold new 
proposal to demonstrate--actually demonstrate altering the 
orbit of an asteroid. I wanted to talk today about sort of a 
different aspect than what you've been hearing about which is 
searching for asteroids and that's the necessary first step. 
But once you find asteroids, particularly if you find one on a 
collision course, the question is, ``What do you do? Or what 
can we do?''
    I represent the B612 Foundation and we're a group of 
astronomers, engineers and astronauts concerned about the issue 
of asteroid impacts. Recent developments have now given us the 
potential to defend the Earth against these natural disasters 
and I'll talk about that.
    To develop this capability, we have proposed a spacecraft 
mission to significantly alter the orbit of an asteroid in a 
controlled manner by 2015 and we think it's important that 
there be an actual demonstration and I'll talk about why that 
is later.
    First off. Why would you want to move an asteroid? I think 
we've been hearing a little bit about that and I want to put 
some of these odds that you've been hearing about in a 
different way; their equivalent numbers. You've been asking 
about what are the odds of getting hit by an asteroid? Well, 
rather than saying once per thousand years or so--another way 
to say that is that during your lifetime, during my lifetime, 
everyone in this room, there's a 10 percent chance that there 
will be a 60 meter asteroid that impacts the Earth with an 
energy of a 10 megatons and that's about 700 simultaneous 
Hiroshima sized bombs going off. It's 10 percent.
    It's kind of like a bad lottery but--in that most days 
are--nothing's going to happen, but occasionally you get a bad 
day and there's a one in 50,000 chance that your death, my 
death, everyone in this room along with most of humanity and 
human civilization is going to end all on the same day with the 
impact with a greater than kilometer sized asteroid; one to 
50,000 is pretty small, but that would be the end of it.
    We think that we now have the potential to change these 
odds and what we propose is again actually trying a 
demonstration mission to deflect an asteroid because there's a 
lot of unknown surrounding this. You've been hearing about that 
but the surest way to actually attack any of these unknowns is 
to try something.
    The first time that you attempt to deflect an asteroid 
shouldn't be on the real day because there's going to be many 
surprises in store. The first few missions may not work at all. 
You want to learn those ahead of time before you actually have 
to use such a system.
    So why do we suggest by 2015? Well, again, the time to 
test, learn and experiment is now because we have just recently 
developed or are developing new advances in space nuclear power 
and high efficiency propulsion that we think makes it possible. 
2015 is challenging, but we think doable and having a clear 
goal, a clear date will, we think, serve to focus the 
development efforts.
    So how big of an asteroid are we proposing to move? The 
demonstration asteroid that you try this test mission on ought 
to be large enough to represent a real risk and also what you 
test should be applicable to larger size asteroids because you 
want to start out fairly small, but you want what you learn to 
be useful through larger asteroids.
    So we're suggesting an asteroid of about 200 meters and a 
200 meter asteroid if it impacts, would be about a 600 megaton 
explosion and as we heard that if that lands in an ocean that 
will likely destroy most coastal cities in that ocean. So 
that's large enough to be a threat.
    Asteroids of about 150 meters across or larger are thought 
to be not single pieces, but rather conglomerations or loosely 
held together groups called, ``rubble piles,'' and so if you 
pick something that's a rubble pile, what you learn will be 
applicable to larger size asteroids. So again, we're picking 
something that's of moderate risk--of major risk but is doable 
we think. Large enough to be doable.
    So what do we mean by significantly alter it? It turns out 
that you don't really need to give an asteroid very much of a 
push to prevent a collision. If you have several decades of 
warning which we expect if these proposed searches are carried 
out, then all you really need to do is if you have several 
decades of notice is to give an asteroid a small impulse. Maybe 
about a centimeter a second. That's about 1/50th of a mile an 
hour.
    Even though the typical asteroid moves around the sun at 
about 70,000 miles per hour, making it 70,000.002 is enough to 
prevent a collision if you've got a decade or so of warning, 
but even though that's a small change in velocity, that's still 
pretty hard because even a 200 meter asteroid weights about 10 
million tons.
    So why do you need to move it in a controlled manner? Well, 
if you don't make it a highly controlled thing, you risk making 
the problem worse. You've seen Armageddon, or movies like that 
where they talk about blowing up an asteroid with a nuclear 
weapon. Well, you stand as much of a chance of making your 
problem worse as making it better and you split the asteroid up 
and what you've done then is turned this rifle bullet heading 
at you into a shotgun blast and now your life has just gotten 
worse.
    Furthermore, you won't really quite know where you're going 
to end up pushing the asteroid and that's not a good situation 
if you're trying to avert a catastrophe. So we are suggesting 
doing this in a controlled slow manner which also has the 
advantage that you can use the same technology for commercial 
reasons--commercial and exploration reasons which has also been 
brought up. So how can you do this?
    Well, first off, conventional rockets like we use today, 
like I've launched on the Space Shuttle and Rusty's flown on 
the Saturn Five, those use chemical propellants. Well, chemical 
propellants basically don't have the umph to move objects of 
this size. So what we are proposing to use is a nuclear powered 
spacecraft using high energy propulsion such as an ion or 
plasma engine. Those are currently in development at NASA today 
as part of the Prometheus Project.
    In fact, the thrust and power requirements that we've 
discussed for moving a 200 meter asteroid are about the same as 
the Jupiter Icing Moons Orbiter and that's a spacecraft that's 
currently planned for launch in around 2012. So we're 
suggesting that you could use similar hardware to do this 
demonstration mission.
    So this spacecraft would fly to an asteroid rendezvous and 
land on and attach to this small asteroid and push on it and by 
continuously thrusting for some period of months you could 
slowly, slowly, slowly alter the velocity by a fraction of a 
centimeter per second and we could measure that from the Earth 
so we could verify that it's worked and then we say, well, what 
can we learn from this?
    Well, remember that this is not really a planetary 
protection system, but it's a first attempt to learn more about 
the mechanics of asteroid deflection because like I said, a lot 
of technical complications and unknowns about asteroids 
themselves, their structure, what they're made of, but the way 
to make progress I think is to build, fly and test.
    You need to go there to find out the questions that you 
don't even know yet. And besides the benefit of actually being 
able to demonstrate that you can do this there's a lot of 
interesting scientific questions you can answer at the same 
time. Again, the best way to learn about asteroids is to go 
there.
    So how does this fit into NASA's New Exploration 
Initiative?
    Well, in the near term, we think this mission would be an 
ideal way to flight test the nuclear propulsion systems already 
under development as part of ``Project Prometheus.'' It could 
also serve as a precursor to a crewed mission, meaning with 
people on board to go visit an asteroid.
    These missions have been proposed as an intermediate step 
to test your spacecraft systems for eventual longer term 
missions to Mars. I would personally love to go on one of those 
missions.
    In the longer term, the ability to land on and manipulate 
asteroids is an enabling technology for extending human and 
robotic presence throughout the solar system.
    If we're to truly open up the solar system, this mission we 
feel is a good way to start. It's likely that someday we're 
going to use asteroids for fuel, building materials or simply 
space habitats, mining, people are going to earn money off 
this. And the B612 Mission would mark a fundamental change in 
spacecraft in that it would actually alter in a measurable way 
an astronomical object rather than simply observing it.
    We can become active participants in the cosmos versus just 
being interested observers. Human beings need to eventually 
take charge of our own destiny in this manner or we will some 
day go the way of the dinosaurs when the next great asteroid 
impact occurs. Thank you.
    [The prepared statement of Dr. Lu follows:]

  Prepared Statement of Dr. Edward Lu, NASA Astronaut and President, 
                            B612 Foundation
    Thank you for the opportunity today to discuss a bold new proposal 
to demonstrate altering the orbit of an asteroid. I represent the B612 
foundation, a group of astronomers, engineers, and astronauts, 
concerned about the issue of asteroid impacts. Recent developments have 
now given us the potential to defend the Earth against these natural 
disasters. To develop this capability we have proposed a spacecraft 
mission to significantly alter the orbit of an asteroid in a controlled 
manner by 2015.
    Why move an asteroid? There is a 10 percent chance that during our 
lifetimes there will be a 60 meter asteroid that impacts Earth with 
energy 10 megatons (roughly equivalent to 700 simultaneous Hiroshima 
sized bombs). There is even a very remote one in 50,000 chance that you 
and I and everyone we know, along with most of humanity and human 
civilization, will perish together with the impact of a much larger 
kilometer or more sized asteroid. We now have the potential to change 
these odds.
    There are many unknowns surrounding how to go about deflecting an 
asteroid, but the surest way to learn about both asteroids themselves 
as well as the mechanics of moving them is to actually try a 
demonstration mission. The first attempt to deflect an asteroid should 
not be when it counts for real, because there are no doubt many 
surprises in store as we learn how to manipulate asteroids.
    Why by 2015? The time to test, learn, and experiment is now. A 
number of recent developments in space nuclear power and high 
efficiency propulsion have made this goal feasible. The goal of 2015 is 
challenging, but doable, and will serve to focus the development 
efforts.
    How big of an asteroid are we proposing to move? The demonstration 
asteroid should be large enough to represent a real risk, and the 
technology used should be scaleable in the future to larger asteroids. 
We are suggesting picking an asteroid of about 200 meters. A 200 meter 
asteroid is capable of penetrating the atmosphere and striking the 
ground with an energy of 600 megatons. Should it land in the ocean (as 
is likely), it will create an enormous tsunami that could destroy 
coastal cities. Asteroids of about 150 meters and larger are thought to 
be comprised of loose conglomerations of pieces, or rubble piles, while 
smaller asteroids are often single large rocks. The techniques we test 
on a 200 meter asteroid should therefore also be applicable to larger 
asteroids.
    What does ``significantly alter the orbit'' mean? If proposed 
asteroid searches are enacted, we expect to have decades or more of 
warning before an impact. Given this amount of warning, to prevent an 
impact only requires that the orbital velocity of an asteroid be 
altered by a small amount, less than of order 1 cm/sec, or about .02 
MPH. This is a tiny velocity increment, considering that the orbital 
speeds of asteroids are of order 70,000 MPH. However, this is still a 
very difficult task since the mass of a 200 meter asteroid is of order 
10 million tons.
    Why does the asteroid need to be moved in a ``controlled manner''? 
If the asteroid is not deflected in a controlled manner, we risk simply 
making the problem worse. Nuclear explosives for example risk breaking 
up the asteroid into pieces, thus turning a speeding bullet into a 
shotgun blast of smaller but still possibly deadly fragments. 
Explosions also have the drawback that we cannot accurately predict the 
resultant velocity of the asteroid--not a good situation when trying to 
avert a catastrophe. Conversely, moving an asteroid in a controlled 
fashion also opens up the possibility of using the same technology to 
manipulate other asteroids for the purposes of resource utilization.
    How can this be accomplished? This mission is well beyond the 
capability of conventional chemically powered spacecraft. We are 
proposing a nuclear powered spacecraft using high efficiency propulsion 
(ion or plasma engines). Such propulsion packages are currently already 
under development at NASA as part of the Prometheus Project. In fact, 
the power and thrust requirements are very similar to the Jupiter Icy 
Moons Orbiter spacecraft, currently planned for launch around 2012. The 
B612 spacecraft would fly to, rendezvous with, and attach to a suitably 
chosen target asteroid (there are many candidate asteroids which are 
known to be nowhere near a collision course with Earth). By 
continuously thrusting, the spacecraft would slowly alter the velocity 
of the asteroid by a fraction of a cm/sec--enough to be clearly 
measurable from Earth.
    What will we learn from this? It is important to remember that this 
mission is merely a first attempt to learn more about the mechanics of 
asteroid deflection. There are a number of technical complications, as 
well as many unknowns about the structure and composition of asteroids. 
However, the way to make progress is to build, fly, and test. Much of 
what we will learn is generic to many proposed asteroid deflection 
schemes, with the added benefit of being able to answer important 
scientific questions about asteroids themselves. The best way to learn 
about asteroids is to go there.
    How does this fit into the new Exploration Initiative at NASA? In 
the near term, this mission would be an ideal way to flight test the 
nuclear propulsion systems under development as part of the Prometheus 
Project. It could also serve as a precursor to a crewed mission to 
visit an asteroid. Such missions have been proposed as intermediate 
steps to test spacecraft systems for eventual longer term crewed 
missions to Mars.
    In the longer term, the ability to land on and manipulate asteroids 
is an enabling technology for extending human and robotic presence 
throughout the solar system. If we are to truly open up the solar 
system, this mission is a good way to start. It is likely that someday 
we will utilize asteroids for fuel, building materials, or simply as 
space habitats. The B612 mission would mark a fundamental change in 
spacecraft in that it would actually alter in a measurable way an 
astronomical object, rather than simply observing it. Human beings must 
eventually take charge of their own destiny in this manner, or we will 
someday go the way of the dinosaurs when the next great asteroid impact 
occurs.

    Senator Brownback. Thank you, Dr. Lu. Mr. Schweickart. I 
guess both of you having traveled to space that's--thank you 
for being here.

STATEMENT OF DR. RUSSELL L. SCHWEICKART, CHAIRMAN OF THE BOARD, 
                        B612 FOUNDATION

    Dr. Schweickart. Thank you for holding hearings, sir. I'll 
deal a bit more with some of the policy issues implied in 
what's been said today in previous testimony. I think it is 
extremely important and reflected to a certain extent by the 
questions you've been asking yourself for people to get a 
picture of what it is that we're talking about. And so in 
addition to repeating, you know, that Near Earth Asteroids in 
the hundreds of thousands pose an occasional but substantial 
threat to life. Let me give you a couple of specific examples.
    As Ed said a moment ago, we're all talking about the same 
elephant and giving you a different snapshot of it. It's all 
basically the same statistical data, but we're trying to give a 
realistic picture. So let me try it this way.
    Last night something on the order of hundreds of thousands 
to a million bits and pieces of asteroids and comets hit the 
Earth. The people that looked up and saw them called them, 
``shooting stars.'' That's what you and I would call them if we 
happened to be looking up on a clear night as well. They don't 
do any damage as you know because the atmosphere protects us.
    But getting a little bit bigger and of course a little 
fewer of them, a little less frequent with the impacts. If we 
took a Near Earth Asteroid the size of this room, one of those 
is going to hit us about once every 2 to 3 years and that would 
in fact also not do much damage but that would in fact result 
in something on the order of a 10 to 15 kiloton, about a 
Hiroshima size explosion in the upper atmosphere. That is 
something the size of this room every 2 to 3 years.
    Now, getting a bit bigger and where it starts getting 
dangerous, step outside and picture something the size of the 
U.S. Capitol Building. Now, have that come flying at the Earth 
at about 20 times the speed of a rifle bullet, if you will. 
That's going to happen on the order of every few hundred years 
to a thousand years, and in that case, we're going to have an 
explosion the size of the largest nuclear weapon in the U.S. 
arsenal, something on the order of 10 to 15 megatons of energy.
    That again compares with the Tunguska Event of 1908 that we 
heard about earlier or a little bit larger if something like 
that happened over--if the U.S. Capitol flew at the U.S. 
Capitol it would destroy the Washington Metropolitan area 
totally. It wouldn't hit the surface. It would actually explode 
something 10 to 20,000 feet above the Capitol, but it would 
decimate everything underneath it for the whole metropolitan 
area.
    Now, that particular size that I just related is the 
smallest thing that we have all been talking about detecting 
ahead of time. That is something down in the vicinity of 100 
meters in diameter, so that gives you an idea. That's the 
smallest thing that we're all up here proposing that the 
Congress direct that NASA, NSF, whoever take under their wing 
to get early warning and intelligence on this threat to public 
safety.
    Protection of the public--so I'll go on from those 
examples. Protection of the public from this hazard, and as I 
say there's something around 200,000 of these things to be 
discovered yet that circle around the sun right now. And the 
protection from this hazard depends entirely on increasing the 
capability of our current asteroid detection and tracking 
program.
    This is a known hazard for which public safety is 
critically dependent on timely information gathering, as is the 
case in all intelligence about threats to public safety.
    The hazards posed by Near Earth Asteroids will become 
widely know by the general public as the detection and tracking 
programs shift their focus to the far more numerous, but very 
dangerous smaller NEOs of--and when I say ``smaller NEOs,'' I'm 
talking about the size of the U.S. Capitol Building.
    Close calls with NEOs in the future will trigger a growing 
public concern and commensurate expectation that the government 
is doing something about this. The government is doing 
something to protect them. At the moment, that is not the case 
at all. The government is doing nothing to actually protect 
people from any NEOs which are coming our way to hit us. We are 
detecting them, but we're not yet providing actual or active 
protection.
    Unlike other natural disasters, this hazard that we're 
talking about here is both predictable and preventable, using 
technologies that are being developed by NASA today in its 
Prometheus Program.
    What is missing today is the goal to explore these Near 
Earth Asteroids to gather the critical understanding necessary 
to ultimately protect the public from this threat.
    Near Earth Asteroids--well, let me just say happily Near 
Earth Asteroids are not only a threat. Near Earth Asteroids are 
also a rich exploratory--exploration target, excuse me, for 
both scientific and economic benefit. Asteroids are easily 
accessible gold mines of information about the origins of the 
solar system.
    They also, and perhaps more importantly, contain a wealth 
of resources for utilization in space which are far more 
accessible than resources on the moon. In fact, as in the case 
with the moon, the Near Earth Asteroids can serve as stepping 
stones to Mars.
    It is not and probably should not be NASA's job to protect 
the Earth from asteroid impacts, but it is NASA's job to 
develop space technologies and capability to serve humanity. 
Since Near Earth Asteroids represent both an opportunity for 
and a threat to humanity and NASA is currently seeking mission 
opportunities for its Prometheus Program, it is entirely 
appropriate that a portion of its efforts be directed to this 
end.
    Therefore, B612 Foundation of which both Ed and I are 
representing here, call today on the Congress to task NASA 
first with increasing the capability of the current Space Guard 
Survey consistent with the recommendations of the recent NASA 
NEO Science Definition Team Report which you've heard reported 
on. In other words, we need, absolutely need better 
intelligence to protect the public.
    Second, we call on Congress to direct NASA to incorporate 
the B612 Mission Goal to demonstrate the capability to land on, 
explore and deflect an asteroid as part of it Prometheus 
Program.
    And third, we call on Congress to request that OSTP 
initiate a high level study to develop a U.S. Government Policy 
for both national and international response to deflection of 
Near Earth Asteroids. This is not, as you're well aware, a 
domestic problem only. This is a global problem and we need to 
be coordinating around this planet with means to protect life 
in the future.
    I'd like to emphasize in closing something that Ed alluded 
to and that is for the first time in the history of humanity, 
we have developed the technology which will enable us, provided 
we focus on it, to protect the future of life on this planet. 
Up until this time, we've been lucky in this shooting gallery. 
The dinosaurs were not lucky. We now have a chance. What we've 
got to do is focus on it and take responsibility for the future 
of life on this planet and today we have that possibility. 
Thank you very much, sir, and we'd be happy to answer any 
questions.
    [The prepared statement of Dr. Schweickart follows:]

Prepared Statement of Russell L. Schweickart, Chairman, B612 Foundation
    Chairman Brownback, Senator Breaux, members of the Committee:
Introduction
    First I'd like to thank you for the invitation to speak with you 
today about this emerging public policy issue of near Earth objects 
(NEOs) threatening life on Earth. One might have thought, just a few 
years ago, that the subject of asteroids was one for space wonks and 
wanna-be astronauts and astronomers. But today the realization is 
rapidly dawning on the media and the general public that asteroids are 
a subject of more than passing interest! More and more people are 
coming to know that some few of these asteroids do not silently pass 
the Earth, but indeed crash in, largely unannounced. On the rare 
occasions when this happens they can wreak havoc of a magnitude 
unprecedented in human history. At the upper limit impacts by large 
asteroids have caused global destruction leading to the virtually 
instantaneous extinction of life for most of the species living at the 
time. The dinosaurs were momentary witnesses to a billion megaton event 
of this kind 65 million years ago. At the lower limit of concern, but 
occurring much more frequently, we are dealing with events with an 
explosive force of 10-15 megatons. It is worth pointing out, however, 
that these small, most frequent events are more powerful than the blast 
from the most powerful nuclear weapon in the current U.S. nuclear 
arsenal.
    Given the extremely low frequency of these natural events in 
combination with the extremely grave consequences when they occur, we 
find ourselves challenged to properly place this subject in our normal 
list of priorities. Inattention to infrequent events, regardless of 
their impact, is the ``default'' solution of choice given the crowd of 
issues continually burning around our feet.
    Therefore the Committee is to be congratulated for its foresight 
and exemplary public service in realizing the importance of dealing 
with this issue now.
History
    Perhaps the best logic path to bring the Committee to appreciate 
our recommendations for action is to briefly outline the key realities 
the founders of the B612 Foundation faced when we first came together 
back in October 2001. We are primarily a group of technical experts 
familiar with or working within the fields of space exploration and 
planetary science. We are astronauts, astronomers, engineers and a few 
others who are knowledgeable about the subject of comets and asteroids 
and their history of impacts with the Earth and other solar system 
bodies. We came together out of a deep concern that the threat to life 
implied in our knowledge of near Earth asteroids (NEAs) was not 
resulting in any organized effort to take action to protect the public 
from this hazard. We came together to explore whether or not something 
could be done, and if so, whether we could trigger a program to protect 
the public.
    In summary, we faced the following facts:

  (1)  Asteroid impacts with Earth have, do, and will continue to occur 
        with devastating consequences to life.

  (2)  Our detection program (the Spaceguard Survey) has produced a 
        good statistical characterization of the overall threat and 
        actual knowledge that at least 60 percent of the asteroids 
        larger than 1 kilometer in diameter will not strike the Earth 
        in the next 100 years.

  (3)  Many impacts by asteroids less than 1 km in diameter, however, 
        which occur hundreds of times more frequently than those over 1 
        kilometer, will cause unacceptable devastation at both local 
        and regional levels.

  (4)  The increasing capability of our detection programs in the next 
        several years will result in a dramatic increase in the 
        discovery rate of these smaller but very dangerous asteroids.

  (5)  The media and the general public will become ever more aware of 
        this threat and concerned that something should be done about 
        it.

  (6)  A known threat that can potentially destroy millions of lives 
        AND can be predicted to occur ahead of time, AND prevented, 
        cannot responsibly go unaddressed.

    This inexorable logic led us to decide to take action and examine 
whether preventive measures could be taken to mitigate this threat, and 
if so, what specific course of action we would recommend.
The Challenge
    It became immediately clear to us that the combination of advanced 
propulsion technologies and small space qualified nuclear reactors, 
both operating in prototype form already, would be powerful enough, 
with reasonable future development, to deflect most threatening 
asteroids away from a collision with the Earth, given a decade or more 
of advance warning.
    Nevertheless we saw two immediate problems.
    First we lack the specific knowledge of the characteristics of NEAs 
necessary to design anything approaching a reliable operational system. 
We could readily show that the technology would exist within a few 
years to get to and land on an asteroid. We also determined that after 
arriving at the asteroid we would have enough propulsive energy 
available to successfully deflect the asteroid from an Earth impact a 
decade or so later. What was missing however was knowledge about the 
structure and characteristics of asteroids detailed enough to enable 
successful and secure attachment to it.
    Second we recognized that before we would be able to gather such 
detailed information about NEAs there would likely be many public 
announcements about near misses and possible future impacts with 
asteroids which would alarm the general public and generate a growing 
demand for action. We felt strongly that there needed to be some 
legitimate answer to the inevitable question which will be put to 
public officials and decision makers, ``and what are you doing about 
this?''
    These two considerations led us to the conclusion that the most 
responsible course of action would be to mount a demonstration mission 
to a NEA (one of our choosing) which would accomplish two essential 
tasks: (1) gather critical information on the nature of asteroid 
structure and surface characteristics, and (2) while there, push on the 
asteroid enough to slightly change its orbit thereby clearly 
demonstrating to the public that humanity now has the technology to 
protect the Earth from this hazard in the future.
    We furthermore determined that this demonstration mission could be 
done with currently emerging capabilities within 10-12 years.
    We therefore adopted the goal of ``altering the orbit of an 
asteroid, in a controlled manner, by 2015''.
    Reflecting the work that we have done to bring this goal to 
realization, a number of us wrote a descriptive article for Scientific 
American magazine entitled, ``The Asteroid Tugboat.'' Scientific 
American published it in the November 2003 issue of the magazine. I 
have provided reprints of this article to the Committee and I would 
like to submit a copy with this testimony and ask that it be 
incorporated in the record.
Implementation
    A key to implementing this mission is NASA's Prometheus Program. 
Shortly after B612 Foundation began work on outlining a mission to 
explore and deflect an asteroid NASA announced the formation of its 
Prometheus Program to develop and demonstrate technologies to permit 
routine human and robotic activity in space ``beyond low Earth orbit''.
    The key technologies which NASA recognized would enable this 
capability are identical with what we had determined were necessary to 
demonstrate the capability to land on and deflect a near Earth 
asteroid, i.e., high performance electric propulsion systems and the 
space nuclear electric power systems to power them. Shortly after 
announcing the Prometheus Program NASA announced the Jupiter Icy Moons 
Orbiter (JIMO) mission complete with schematic representations of the 
spacecraft. Integral to the design of this mission were the very high 
performance engines and space nuclear power system which would be 
necessary to enable our B612 mission. We therefore adopted, as an 
explicit element of our design, the JIMO/Prometheus capabilities, 
recognizing that this was the most likely path to meeting the 
demonstration goal that we had set.
    Mounting a mission to assure the public that when we discover an 
asteroid ``with our name on it'' we can deflect it from a life 
threatening impact on Earth does not require the development of 
additional new technologies. The key capabilities required are already 
``in the pipeline'' of the existing Prometheus Program. No new NASA 
money is required, nor is a change in NASA's mission called for. What 
is required is that the B612 mission be incorporated within the 
Prometheus Program . . . a matter of policy.
    Indeed, if one examines the technical requirements associated with 
the B612 mission, one sees not only a mission ideally suited to 
demonstrating the Prometheus technology, but a mission notably less 
demanding than the currently planned JIMO mission. One could then quite 
easily consider the B612 mission as either a follow-on or a precursor 
to the JIMO mission, depending on NASA's technical judgment as to where 
it fits most logically in their mission model.
    The B612 mission also fits well into the President's Space 
Exploration Initiative. This mission both utilizes and graphically 
demonstrates the key enabling technologies for routine future 
operations ``beyond low Earth orbit''. It is an ideal way to 
demonstrate the technology and the greatly enhanced propulsive 
capability implicit in the Prometheus exploration program. In executing 
such a mission humankind will, for the first time in its history, have 
altered the trajectory of a cosmic body, a demonstration of evolving 
capability in space technology and exploration if there ever was one!
Additional Perspective
    A few final comments are perhaps appropriate.
    Near Earth asteroids are a reality which is here to stay. In fact 
they will become far more prominent in the public mind as time goes on 
and our detection of them continues to improve. It is therefore 
appropriate that we take a more circumspect look at these sometimes 
unruly, but ever-present, neighbors. Near Earth asteroids are, in fact, 
both a threat and an opportunity.
    Certainly we need to learn more about our capability to protect 
life here on Earth, and the sooner the better.
    Visiting asteroids can also teach us a great deal about the origins 
of the solar system, and perhaps even the origins of life. Unlike the 
material of the Earth, which has been melted and processed through 
extensive geologic activity, the materials of small asteroids have not 
been so extensively reprocessed. They are fossil building blocks left 
over from the formation of the planets and as such can teach us a great 
deal about the original material from which the planets formed.
    Perhaps even more important, asteroids, and especially the near 
Earth asteroids, are also the most readily accessible and rich 
reservoir of non-terrestrial resources available to us. The new space 
initiative has emphasized our determination to return to the Moon and 
then extend our capability outward to Mars and beyond. One of the 
purposes advocated for returning to the Moon is to explore and 
potentially develop the capability to utilize the resources there for 
human benefit. The possibility of extracting oxygen, water and perhaps 
other materials from lunar soils has long been advocated as a potential 
capability for reducing the cost of future space operations.
    Yet these same resources, and others in rich abundance, 
characterize the makeup of asteroids. Unlike lunar materials, which are 
largely depleted of heavy minerals, the asteroids are quite rich in 
metallic elements, as well as those minerals which may provide water 
and oxygen. Furthermore it is significantly less expensive to fly to 
and from selected near Earth asteroids than to and from the Moon due to 
the virtual absence of gravitational forces associated with these 
bodies.
    When commercial, entrepreneurial activity emerges into deep space 
it will undoubtedly include the development and exploitation of in-situ 
resources and services. Given the critical importance of benefit/cost 
analysis in any commercial venture it would be surprising if 
utilization of asteroidal resources, especially water, is not one of 
the first deep space initiatives attracting private capital.
    Given then the infrequency of actually having to deflect an 
asteroid in order to avoid an Earth impact it is unlikely that humanity 
will ever need to develop a stand-alone planetary defense system. 
However, given the commercial, as well as the scientific value implicit 
in near Earth asteroids it is highly likely that operations to and from 
the asteroids will become a routine part of human space operations. One 
can readily imagine a time when visiting, using and even moving near 
Earth asteroids becomes a routine human capability. Simply calling on 
the ``Ace Asteroid Mining and Moving Company'' to nudge asteroid 2018 
FA322 gently out of the way may then be all that is required to prevent 
an otherwise devastating event.
    While the above scenario is somewhat fanciful, it is, given time, 
only slightly so. In the meanwhile, in the immediate future, we will be 
discovering an increasing number of potentially life threatening NEAs 
and the public will become justifiably concerned. Without a legitimate 
answer to this concern for their safety this concern could morph into 
alarm.
    While many lives are lost every year in natural disasters of one 
kind or another, there are few natural disasters that can reliably be 
predicted, much less prevented. Throughout human experience we have 
been faced with comforting and compensating the devastated after the 
disaster is over. With near Earth asteroid impacts, however, we are 
confronted with a massive natural disaster that can be both predicted 
AND prevented, and the public will come to understand that this is the 
case.
    Given the justifiable public expectation of being protected from 
both natural and manmade disasters it is incumbent on us to address 
this known threat responsibly. We therefore make the following specific 
recommendations:

  (1)  We call on the Congress to task NASA with increasing the 
        capability of the current Spaceguard Survey consistent with the 
        recommendations of the recent NASA Near-Earth Object Science 
        Definition Team report.\1\
---------------------------------------------------------------------------
    \1\ Study to Determine the Feasibility of Extending the Search for 
Near-Earth Objects to Smaller Limiting Diameters, Report of the Near-
Earth Object Science Definition Team, August 22, 2003.

  (2)  We call on Congress to direct NASA to incorporate the B612 
        mission goal of demonstrating the capability of landing on, 
        exploring, and deflecting an asteroid as part of its Prometheus 
---------------------------------------------------------------------------
        Program.

  (3)  We call on Congress to request that OSTP initiate a high level 
        study to develop a U.S. Government policy for both national and 
        international response to the deflection of near Earth 
        asteroids.
                               Attachment
                               
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    Senator Brownback. Mr. Griffin--Dr. Griffin, how many times 
has the Earth been struck by a substantial sized asteroid? By 
this, I mean something a 100 meters or greater that we know 
about or that we have a pretty good idea it took place. You've 
cited a couple, but how many times? Do we know?
    Dr. Griffin. I would have to defer to someone with greater 
expertise on that than myself, but in fact I don't think the 
answer is known. We have catalogued around the globe several 
dozen, many dozen known impact events by the scars that they 
leave behind.
    Senator Brownback. Known impact events that had a 
substantial impact on the Earth in that particular area?
    Dr. Griffin. Right. Like the meteor crater in Arizona or 
larger. OK. Many dozen of those are known. Some of them 
ancient. Some of them relatively new in geologic terms. But the 
Earth heals itself quite rapidly. The Earth is not a good 
witness plate for such events. I'll look at the moon and it 
probably offers a better estimate of what really happens to a 
celestial body over the course of time.
    Senator Brownback. And it's actually even a smaller target 
to hit than the Earth so----
    Dr. Griffin. That's correct. Senator, just by chance I 
happen to have been asked to provide a lecture somewhat along 
those very lines so I can tell you that the answer is greater 
than hundreds of thousands of times the Earth being hit in its 
history by objects a hundred meters and greater in size.
    Now, we don't have much evidence of that in the form of 
scars. We do see scars from only about 200 impacts that we're 
aware of at this time, but again looking at the moon, you can 
take each crater there and multiply by about 20 to 30 and know 
that that's hit the Earth--that we have been hit--the Earth 
that many times.
    Senator Brownback. Is that where you come up with that 
number as you look at the moon and then multiply out the number 
of craters?
    Dr. Griffin. What I would refer you to as the most 
authoritative thing, sir, would be in fact the report sitting 
in front of Grant Stokes here that he co-chaired in terms of 
the development. And there is within that report a graph which 
give you the best knowledge that we have, statistical knowledge 
of the frequency of asteroids in near Earth space and you can 
simply utilize that graph at any size asteroid you want and get 
the number and the size and power of any of these asteroids. So 
I refer you to that excellent report.
    Senator Brownback. Dr. Stokes. Do you know the answer to 
that question?
    Dr. Stokes. What we've done to come up with the best 
estimate of impact actually looks at a number of things. One 
looks a lunar cratering rate to get an estimate.
    One can also get an independent estimate looking at the 
performance of the search systems that have been ongoing which 
have been making a lot of progress recently. And in fact, you 
can take all the search volume that they've done, and all the 
detections and all the re-detections, use that to estimate an 
impact rate. And in fact, it's getting to the point where all 
of those numbers are beginning to come together and be 
consistent and so we're very happy with the about 1,100 larger 
than a kilometer size. We believe that's a good estimate.
    Once you have that estimate and then work some 
extrapolations from there which can be tied down at various 
sizes from the moon and also the experience of very small 
events, things hitting LDEF for instance, micrograins, you can 
put those all into a continuum and the story sticks together 
very well.
    On that basis, we can then estimate the rate of impacts as 
a function of size, which is where we came up with the numbers 
that I previously had quoted.
    Senator Brownback. Well, how many times this last century 
has the Earth been struck by a substantial asteroid that caused 
at least significant localized damage?
    Dr. Griffin. I think we know of two specific instances. One 
in Siberia in 1908. One again in Russia in 1947, both of which 
caused substantial damage on the ground. We know of a number of 
other events that range down to an asteroid hitting a car in 
the Eastern seaboard a few years ago and----
    Senator Brownback. That would be a real unlucky day, 
wouldn't it? I mean, you're just sitting here in your car and--
--
    Dr. Griffin. Actually, it hit a car in a garage and I think 
it vastly increased the price of that car that day.
    Senator Brownback. That's not so unlucky.
    Dr. Griffin. There certainly have been many other events 
where things get down to the ground many of which land in the 
water. Many of which land in unpopulated areas and are not 
seen. Another way to get data is to look at the military 
satellites that look down for events in the atmosphere. They 
routinely detect, you know, modest size objects, but kiloton 
and larger events in the upper atmosphere, so there are 
statistics coming from those as well.
    Senator Brownback. What's the chance of getting 
international cooperation at the operational or funding level 
to get at least the catalogue of these objects?
    Dr. Griffin. Let's see. I think to some extent there is a 
loosely coordinated international effort ongoing now. Most of 
the large surveys are operated in the United States based 
largely on NASA funding, and I think there's a view in the--at 
least Europe and the rest of the world that if NASA's doing 
that maybe we should just let them do that and contribute where 
we can.
    Another place that work has to be done is in following up 
objects. The large surveys where we go out and find a large 
number of these objects, initially finding them is only part of 
the process.
    We also need a continuing stream of observations to develop 
a good orbit and keep track of them. Many of those are provided 
by international sources. Many of them are provided by amateurs 
that are very interested in doing this. Many of them Japanese. 
Eastern Europe in fact has some very active professionals that 
do this.
    And all of that data is sent to a place called, The Minor 
Planet Center in the Harvard Smithsonian in Cambridge, 
Massachusetts where all that data comes together and is used to 
maintain a catalogue of all of the objects. So that is 
chartered by the International Astronomical Union. It is an 
international body that gives discovery credit and monitors 
naming rights and things like that.
    So there is a very international flavor on these after 
discovery and that works actually very well.
    Dr. Schweickart. Yes, just a minor additional comment. 
There is an excellent report that was chartered by the 
Parliament of the United Kingdom several years ago and I also 
recommend that Task Force Report to you. It made excellent 
recommendations in terms of the U.K. jumping in to provide 
resources for this very vital task. Unfortunately, there has 
been no action taken on the excellent recommendations of that 
report. As recently as a couple of months ago in Parliament 
specific recommendations were considered and the bottom line is 
nothing in fact happened.
    Another action has been taken by the OECD. OECD has begun 
to hold several discussions on the issue of mitigation of 
asteroid and comet impacts and what might be done in terms of 
disaster preparedness. There was a meeting a year ago, January 
in Frascati, Italy, but again, there was no expenditure of 
funds.
    What was done there which I would strongly urge, Senator 
Brownback, is that all nations participating in the OECD 
hearing were recommended that they identify a particular 
governmental institutional person to monitor this issue of 
asteroid impacts and their consequences.
    Ironically, while NASA is today tasked with conducting 
certain surveys, there is no identification within the U.S. 
Government of direct responsibility for monitoring this as a 
public safety issue. And that would be--that is in fact a 
recommendation by a number of organizations and I would 
encourage that that be looked at by this committee.
    Senator Brownback. I think that's one of the proposals in 
the Rohrabacher bill from the House side.
    Dr. Griffin. Yes, it is.
    Senator Brownback. That we're looking at here from this 
side. I understand that maybe some of you already have 
commented on this and I haven't picked it up. But the American 
Institute of Aeronautics and Astronautics held a conference on 
protecting the Earth recently and were any of the 
recommendations that you've put forward recommended by that 
conference or does anybody----
    Dr. Griffin. Yes, sir, I can address that. In fact, I 
talked yesterday by phone with the General Chairman of the AIAA 
Conference on protecting the Earth from asteroid and cometary 
impacts. There is a final report from the conference itself and 
I can, or better yet AIAA, American Institute of Aeronautics 
and Astronautics, can make that conference report available to 
you.
    It has also been compressed and presented or is being 
presented to the AIAA per se as a policy document. They will 
shortly vote on that and there will be an official AIAA 
recommendation, but that has not yet been issued. I can read 
you one final paragraph to give you a flavor of the AIAA 
position. They say: ``Future impacts by comets and asteroids 
are a certainty. Such impacts could have severe consequences 
even ending civilization and humanity s existence. Life on 
Earth has evolved to the point where we can mount a defense 
against these threats. It is time to take deliberate steps to 
assure a successful defensive effort should the need arise.''
    So the AIAA I believe will take a fairly strong position on 
this proposal.
    Mr. Richardson. I would echo that. I'm the President-Elect 
of AIAA for the coming year and a member of the Board of 
Directors and I have followed this and feel quite certain that 
the organization--or the directors will vote affirmatively as 
Rusty has suggested.
    Senator Brownback. Is this a high priority for that 
organization?
    Mr. Richardson. Yes, it is, again, in support of the 
overall conclusions of the study that has been referenced here 
several times and of the President's exploration initiative 
because we believe that it is all tied together.
    Senator Brownback. That this should be a key part of the 
President's overall exploration initiative?
    Mr. Richardson. I believe that's correct.
    Senator Brownback. It seems to me that it ties in with it 
as well and that there's an additional--this huge safety factor 
and issue here for the area that might get hit or all of 
civilization even in the most catastrophic----
    Mr. Richardson. That's correct. The safety issue is a 
little difficult for many people to get their arms around 
because if you take other threats for example, you can 
calculate quite well the odds that any individual has of being 
struck by lightning and we know that, but most individuals will 
not ever be struck by lightning.
    However, we know that in any given year the odds are quite 
small that the Earth will be struck by a major asteroid. But we 
know that sooner or later that will occur and when it occurs 
everyone will die. Unlike most other catastrophic hazards to 
life and property which affect only a small subset of the human 
race, it is inevitable that an asteroid will strike the Earth 
and that it will have the capability to essentially take out 
the whole plant and that's what's different about this 
particular hazard.
    Dr. Griffin. Senator Brownback, if I could try a slightly 
different perspective to the question that we're discussing 
right now. If you think about the asteroids as a mixed bag, 
that is there's good news and bad news. The bad news we've been 
focusing on here today, but there's good news there in terms of 
resources as well as scientific knowledge.
    But if I just deal with resources, let me say that the 
whole President's new initiative in space to enable routine 
operations of human kind beyond low Earth orbit will ultimately 
depend upon accessing resources that are already in space and 
utilizing them.
    Asteroids are the ideal source of that because you don't 
have to lift them off the moon number one because it has such 
low gravity. They're right there with no gravity around them 
and they're actually richer than the lunar soils. So in terms 
of commercial private enterprise activity in space, I think 
there's no question but that private investment, once there is 
a buyer of the products and services, private investment will 
find it profitable to mine and produce--to mine minerals or 
whatever, oxygen, water, you name it, and provide services 
associated with the Near Earth Asteroids.
    Now, when that commercial operation gets going, the once 
every three or four hundred years that you will need to deflect 
an asteroid because we find one heading our way, will be a 
simple matter of contracting with the Ace Mining and Moving 
Company to push that one a bit you know in what they're doing 
and get it out of the way.
    So I think that you're looking at routine operations 
developing around asteroids and almost as a natural byproduct 
of that, the capability to protect the Earth will emerge. So I 
think there is a great deal of correlation between the overall 
capability that we're looking for and the long-term development 
of the space environment beyond low Earth orbit as in the 
President's initiative.
    Senator Brownback. Well, gentlemen, thank you very much for 
joining me today. We'll keep the record open for the requisite 
amount of time if you would care to add to your comments that 
were put forward here today.
    I did submit a series of questions and I don't--I think 
some of them were to you gentlemen from Mr. Nelson and so those 
will be submitted to you. And if you could respond to those, I 
know Senator Nelson would certainly appreciate that as well.
    Very interesting. Very illuminating and as usual a resource 
issue. And resources is always about a competing set of 
interests in it and hopefully we can get more resources to this 
for both the protection and for the opportunity that they 
represent.
    God speed to you. It's a very interesting field that each 
of you are involved in and quite important for the future of 
society, future of humanity.
    Thank you for coming. The hearing is adjourned.
    [Whereupon, at 4:19 p.m., the hearing was adjourned.]

                            A P P E N D I X

       Prepared Statement of Congressman Dana Rohrabacher (R-CA)
    I want to thank Senator Brownback for his leadership in holding 
today's hearing on the threat posed by near Earth objects (NEOs). As 
Chairman of the Space and Aeronautics Subcommittee, I've made 
addressing this threat one of my top priorities. Our hearings have 
revealed that monitoring and tracking NEOs such as comets and asteroids 
is not only vitally important to the advancement of the field of 
astronomy, but also critical in identifying NEOs that threaten the 
Earth. Recent press accounts of asteroids passing close to the Earth 
have raised public awareness of the possibility that these objects 
could one day hit the Earth with potentially catastrophic consequences. 
Given the vast number of asteroids and comets that inhabit Earth's 
neighborhood, greater efforts for tracking and monitoring these objects 
are critical.
    This is why I introduced H.R. 912 the ``Charles `Pete' Conrad 
Astronomy Awards Act,'' which passed the House last month, and H.R. 
3813 the ``George E. Brown, Jr. Near-Earth Objects Survey Act.'' It is 
vital that we use all available public and private sector resources for 
tracking and monitoring NEOs.
    H.R. 912 authorizes the NASA Administrator to give one award each 
year to the amateur astronomer or to the group of amateur astronomers 
that discovered the intrinsically brightest near-Earth asteroid among 
the near-Earth asteroids discovered during the preceding year by 
amateur astronomers, and another award to the amateur astronomer or 
group of amateur astronomers that made the greatest contribution during 
the preceding year to the Minor Planet Center's catalogue of known 
asteroids. The recipients of the awards, in the amount of $3,000, are 
limited to U.S. citizens and permanent residents.
    This bill is a tribute to Pete Conrad for his tremendous 
contributions to the aerospace community over the last four decades. 
Pete Conrad was a pilot/explorer/entrepreneur of the highest caliber. 
He commanded Apollo XII, and during that mission became the third man 
to walk on the Moon. I find no better way to honor Pete Conrad than to 
establish an annual astronomer's award for future asteroid discovers in 
his name. He always wanted people to be looking up with a positive 
``can-do'' American spirit--exemplified by his historic description of 
landing on the Moon.
    H.R. 3813 authorizes the NASA Administrator to plan, develop, and 
implement a near Earth objects survey program for the purpose of 
detecting, tracking, cataloguing, and characterizing physical 
characteristics of near-Earth asteroids and comets 100 meters or 
greater in diameter. The bill also amends the NASA Act of 1958 by 
directing the agency to use its resources and the expertise of its 
workforce to carry out the NEO survey program--so as to provide warning 
and mitigation of the potential hazards of NEOs that threaten impact 
with the Earth. The bill authorizes appropriations in the amount of $20 
million for Fiscal Years 2005 and 2006 to enable NASA's efforts in this 
area.
    In his agency vision statement, NASA Administrator Sean O'Keefe 
talked about the planet's environment. I believe protecting our planet 
from impacting asteroids should also be one of NASA's major concerns. A 
few years ago, NASA initiated the ``Spaceguard'' plan, which is 
intended to catalog at least 90 percent of them by 2010. Presently, the 
Spaceguard program appears to be on track, but its focus is on 
surveying asteroids large enough to destroy all life on Earth. Surveys 
of smaller asteroids with the potential to destroy cities, countries, 
and to bring about changes in global climate should also be vigorously 
pursued.
    Of course, the threat of an asteroid hitting the world is a serious 
matter. The idea of a catastrophic asteroid or comet impacting on the 
Earth has garnered much attention in the media and popular culture. 
It's vital for all of us to realize, however, that this is not science 
fiction. We all know that the Earth's moon and many other planetary 
bodies in the solar system are covered with impact craters. Most people 
have heard of the ``dinosaur extinction'' theory or perhaps seen 
pictures of the meteor crater in Arizona. However remote the 
possibility of NEOs striking the Earth and causing worldwide calamity 
in our lifetime, it has happened and it will happen again unless 
mankind is able to detect and possibly avert a catastrophe.
    While the asteroid that killed the dinosaurs is estimated to occur 
once every 100 million years, smaller, yet still very hazardous 
asteroids impact the Earth much more frequently. For example, the 
destructive force of the 1908 Tunguska event in Siberia was roughly 
equal to a 10-megaton blast of TNT caused by an asteroid estimated to 
be about 200 feet Greenland involving an asteroid, which had a 
destructive force measuring 100 kilotons of TNT.
    Ironically, if you look at asteroids from the perspective of our 
national goals in space, they also offer us unique opportunities. In 
terms of pure science, asteroids are geological time capsules from the 
era when our solar system was formed. Even better, they are orbiting 
mines of metals, minerals, and other resources we can use to possibly 
build large structures in space without carrying everything up from the 
Earth. So far, NASA has surveyed 600 asteroids, but this is a small 
fraction of the projected total. What needs to be done now is to fully 
survey the NEO population.
    In closing, it is my hope that H.R. 3813 will bring greater 
attention to the NEO issue by focusing NASA more closely on this 
critical area of study, because NEOs have given the topic of planetary 
defense a serious tone within the scientific community. The first step 
is a thorough tracking of all sizeable NEOs, and H.R. 912 and H.R. 3813 
are modest steps toward this goal. Thank you, Mr. Chairman.

                                  [all]


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