[Federal Register Volume 62, Number 46 (Monday, March 10, 1997)]
[Notices]
[Pages 10879-10880]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-5735]
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NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
[Notice (97-026)]
National Environmental Policy Act; Cassini Mission
AGENCY: National Aeronautics and Space Administration (NASA).
ACTION: Notice of intent to prepare a supplemental environmental impact
statement (SEIS) for implementation of the Cassini mission to Saturn
and its moons.
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SUMMARY: Pursuant to the National Environmental Policy Act of 1969
(NEPA), as amended (42 U.S.C. 4321 et seq.), the Council on
Environmental Quality Regulations for Implementing the Procedural
Provisions of NEPA (40 CFR Parts 1500-1508), and NASA's policy and
procedures (14 CFR Part 1216 Subpart 1216.3), NASA intends to prepare a
supplement to the Cassini mission Final Environmental Impact Statement
(FEIS). The SEIS will focus on updated information pertinent to the
consequence and risk analyses of potential accidents during the launch
and cruise phases of the mission. Such accidents could result in a
release of plutonium dioxide from the three Radioisotope Thermoelectric
Generators (RTG's) and the potential 157 Radioisotope Heater Units
(RHU's) onboard the Cassini spacecraft. The currently planned mission
involves the launch of the Cassini spacecraft from Cape Canaveral Air
Station (CCAS), Florida, during the primary launch opportunity in
October 1997.
FOR FURTHER INFORMATION CONTACT: Mr. Mark R. Dahl, NASA Headquarters,
Code SD, Washington, DC 20546-0001; 202-358-0306.
SUPPLEMENTARY INFORMATION: The planned Cassini mission is an
international cooperative effort of NASA, the European Space Agency,
and the Italian Space Agency, to explore the planet Saturn and its
environment. Saturn is the second-largest and second-most massive
planet in the solar system and has the largest, most visible dynamic
ring structure of all the planets. The planned mission is an important
part of NASA's program for exploration of the solar system, the goal of
which is to understand the system's birth and evolution. The Cassini
mission would involve a 4-year scientific exploration of Saturn, its
atmosphere, moons, rings, and magnetosphere. The Cassini spacecraft
consists of the Cassini Orbiter and the detachable Huygens Probe.
For several months, prior to its arrival at Saturn in June 2004,
the spacecraft would perform scientific observations of the planet. The
planned arrival date at Saturn provides a unique opportunity to have a
distant flyby of Saturn's outer satellite Phoebe. About 3 weeks before
its first flyby of Titan, Saturn's largest moon, the Huygens Probe
would be released for a 2.5 hour parachute descent into Titan's
atmosphere. The probe would sample and determine the composition of
Titan's atmosphere during its descent, and gather data on
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the moon's landscape. The Cassini Orbiter would then continue its
Saturn orbital tour, providing opportunities for ring imaging,
magnetospheric coverage, and radio (Earth), solar, and stellar
occultations of Saturn, Titan, and the ring system. A total of 35 close
Titan flybys have also been planned for the 4-year tour, along with 4
close flybys of selected icy satellites, and 29 more distant satellite
encounters. The scientific information gathered by the Cassini mission
could help provide clues to the evolution of the solar system and the
origin of life on Earth.
The Cassini spacecraft would carry three RTG's that use the heat of
decay of plutonium dioxide to generate electric power for the
spacecraft and its instruments. The spacecraft would also use up to 157
RHU's, each containing a small amount of plutonium dioxide, to generate
heat for controlling the thermal environment of the spacecraft and
several of its instruments.
The Cassini FEIS was made available to Federal, state, and local
agencies, the public, and other interested parties on July 21, 1995. In
addition to the No-Action alternative, the FEIS addressed in detail
three alternatives for completing preparations for, and operating the
Cassini mission to Saturn and its moons. On October 20, 1995, utilizing
the analyses in the FEIS along with other important considerations such
as programmatic, technical, economic, international relations, and
other factors, the Record of Decision selecting the Proposed Action was
rendered.
The Proposed Action consists of completing preparations for and
implementing the Cassini mission to Saturn and its moons, with a launch
of the Cassini spacecraft onboard a Titan IV(SRMU)/Centaur. The launch
would take place at CCAS during the primary launch opportunity in
October 1997. A secondary launch opportunity occurs in December 1997,
with a backup opportunity in March 1999, both using the Titan IV(SRMU)/
Centaur. The primary launch opportunity would employ a Venus-Venus-
Earth-Jupiter-Gravity-Assist trajectory to Saturn; the secondary and
backup opportunities would both employ a Venus-Earth-Earth-Gravity-
Assist (VEEGA) trajectory. The Proposed Action would allow the Cassini
spacecraft to gather the full science return desired to accomplish
mission objectives.
Along with the No-Action alternative (ceasing preparations and not
implementing the Cassini mission), the FEIS evaluated in detail two
other mission alternatives. The March 1999 alternative would have used
two Shuttle flights with on-orbit integration of the spacecraft and
upper stage, followed by injection of the spacecraft into a VEEGA
trajectory to Saturn. Due to the long lead-time in developing and
certifying the new upper stage that would be needed to implement it,
this alternative is no longer considered reasonable. Also, this
alternative would have returned less science than the primary launch
opportunity of the Proposed Action. The other mission alternative
considered in the FEIS was the 2001 alternative, which would use a
Titan IV(SRMU)/Centaur to launch the spacecraft from CCAS in March 2001
on a Venus-Venus-Venus-Gravity-Assist trajectory. A backup opportunity
in May 2002 would use a VEEGA trajectory. The 2001 alternative would
require completing development and testing of a new high-performance
rhenium engine for the spacecraft, as well as adding about 20 percent
more propellant to the spacecraft. Science returns from this
alternative would meet the minimum acceptable level for the mission.
The FEIS analyses demonstrated that completing preparations for and
implementing a normal Cassini mission would not significantly impact
the human environment. The principal concern associated with all
mission alternatives (except No-Action) was with accidents during
launch and operation of the mission that have the potential to result
in a release of plutonium dioxide from the RTG's and/or RHU's onboard
the spacecraft. In response, NASA and the U.S. Department of Energy
(DOE), using the best information available at that time, developed an
array of representative accident scenarios that could potentially
result in a release of plutonium dioxide from the RTG's. NASA and DOE
analyzed the representative accident scenarios with respect to the
consequences and risks. The results of those analyses were presented in
the Cassini FEIS.
Updated results from the continuing tests and analysis have
recently become available for NASA review. This updated data indicates
that there is new information relevant to environmental concerns and
bearing on the impacts of the Proposed Action. NASA has determined that
the purposes of NEPA will be furthered by preparation and issuance of
an SEIS.
The SEIS will address NASA's consideration of the updated data
resulting from the ongoing analysis. The SEIS will compare the updated
data with those in the FEIS and will focus on the areas where the
largest differences in risk are estimated. The SEIS will address the
Proposed Action, the No Action alternative, and the 2001 mission
alternative which is still available to NASA.
Benita A. Cooper,
Associate Administrator for Management Systems and Facilities.
[FR Doc. 97-5735 Filed 3-7-97; 8:45 am]
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