National Environmental Policy Act; Cassini Mission

NATIONAL AERONAUTICS AND SPACE ADMINISTRATION

[Notice 97-040]

National Environmental Policy Act; Cassini Mission

AGENCY: National Aeronautics and Space Administration (NASA).

ACTION: Notice of availability of draft supplemental environmental

impact statement (DSEIS) for 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 policy and

procedures (14 CFR Part 1216, Subpart 1216.3), NASA has prepared and

issued a DSEIS for the Cassini mission. The DSEIS focuses 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 the release of plutonium dioxide from one or

more of the three Radioisotope Thermoelectric Generators (RTG's) and

the approximately 130 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 that begins in early

October 1997.

DATES: Comments on the DSEIS must be submitted in writing and received

by NASA no later than May 27, 1997, or 45 days from the date of

publication in the Federal Register of the U.S. Environmental

Protection Agency's notice of availability of the Cassini mission

DSEIS, whichever is later.

ADDRESSES: Written comments should be addressed to Mr. Mark R. Dahl,

NASA Headquarters, Code SD, Washington, DC 20546-0001. The DSEIS may be

reviewed at the following locations:

(a) NASA Headquarters, Library, Room 1J20, 300 E Street, SW.,

Washington, DC 20546.

(b) Spaceport U.S.A., Room 2001, John F. Kennedy Space Center, FL

32899. Please call Lisa Fowler beforehand at 407-867-2497 so that

arrangements can be made.

(c) Jet Propulsion Laboratory, Visitors Lobby, Building 249, 4800

Oak Grove Drive, Pasadena, CA 91109 (818-354-5179).

In addition, the DSEIS may be examined at the following NASA

locations by contacting the pertinent Freedom of Information Act

Office:

(d) NASA, Ames Research Center, Moffett Field, CA 94035 (415-604-

4190).

(e) NASA, Dryden Flight Research Center, Edwards, CA 93523 (805-

258-3448).

(f) NASA, Goddard Space Flight Center, Greenbelt, MD 20771 (301-

286-0730).

(g) NASA, Johnson Space Center, Houston, TX 77058 (713-483-8612).

(h) NASA, Langley Research Center, Hampton, VA 23665 (757-864-

2497).

(i) NASA, Lewis Research Center, 21000 Brookpark Road, Cleveland,

OH 44135 (216-433-2222).

(j) NASA, Marshall Space Flight Center, AL 35812 (205-544-0031).

(k) NASA, Stennis Space Center, MS 39529 (601-688-2164).

Limited copies of the DSEIS are available, on a first request

basis, by contacting Mark Dahl at the address or telephone number

indicated herein.

FOR FURTHER INFORMATION CONTACT:

Mark Dahl, 202-358-1544.

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 plant

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, it's

atmosphere, moons, rings, and magnetosphere. The Cassini spacecraft

consists of the Cassini Orbiter and the detachable Huygens Probe. The

Huygens Probe would be released for a parachute descent into the

atmosphere of Titan, Saturn's largest moon. 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.

NASA issued the Final Environmental Impact Statement for the

Cassini Mission in July 1995 (hereinafter the ``EIS'') followed by the

associated Record of Decision (ROD) to complete preparation of the

Cassini mission for launch in the October 1997 opportunity, or either

the secondary or backup opportunities, and to implement the mission.

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

approximately 130 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 action selected and documented in the ROD 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 that begins in early October 1997 and

continues into mid-November 1997. A secondary launch opportunity

extends from the end of November 1997 to early January 1998, with a

backup opportunity from mid-March to early April 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 above primary launch

opportunity remains NASA's preferred alternative and Proposed Action

and 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 EIS 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. The other mission

alternative considered in the EIS 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 EIS analyses demonstrated that completing preparations for and

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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 EIS.

Updated results from the continuing tests and analyses have

recently become available for NASA review. This updated data indicates

that there is new information relevant to the environmental impacts of

the Proposed Action.

The DSEIS compares the updated data from the ongoing analyses with

those in the EIS and focuses on the areas where the largest differences

are estimated. The DSEIS addresses the Proposed Action, the No-Action

alternative, and the 2001 mission alternative that is still available

to NASA.

Jeffrey E. Sutton,

Acting Associate Administrator for Management Systems and Facilities.

[FR Doc. 97-9104 Filed 4-8-97; 8:45 am]

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