Douglas Isbell
Headquarters, Washington, DC                                           

October 19, 1994
(Phone:  202/358-1547)

Mary Beth Murrill
Jet Propulsion Laboratory, Pasadena, CA
(Phone:  818/354-5011)

RELEASE:  94-174

CASSINI DRAFT ENVIRONMENTAL IMPACT STATEMENT RELEASED

     The Draft Environmental Impact Statement (DEIS) for the 
Cassini mission to Saturn has been released by NASA and will be 
available for public review and comment for a 45-day period 
beginning Oct. 21.  Cassini is a cooperative scientific mission 
of the U.S. and European space agencies scheduled for launch in 
1997.

     An Oct. 20 notice in the Federal Register will formally 
announce the issuance of the DEIS by NASA and give further 
details on where the public may locate a review copy.  The DEIS 
addresses the potential environmental impacts associated with 
the planned Cassini mission and reasonable mission 
alternatives.

     "We have prepared a comprehensive draft environmental impact 
statement that describes all of the alternatives that are under 
consideration as we shape the Cassini mission," said Dr. Earle 
K. Huckins, Cassini Program Director in the Office of Space 
Science at NASA Headquarters.  "We look forward to the public 
comments on our draft statement during this review period."

     The Cassini mission would send a robotic spacecraft on a 
seven-year journey to the ringed planet after launch aboard a 
Titan IV/Centaur from Cape Canaveral, FL, in October 1997.   
The spacecraft would use a series of gravity-assist swingbys of 
planets including Venus, Earth and Jupiter, to gain enough 
extra energy to reach Saturn, which orbits nearly one billion 
miles from the Sun.  

                    -more-

                      -2-

     Upon arrival at Saturn in 2004, the Cassini spacecraft would 
enter orbit around Saturn to conduct four years of intensive 
studies of the planet, its rings, magnetic environment and icy 
moons.  About three weeks before Cassini's first flyby of 
Titan, Saturn's largest moon, the spacecraft would release the 
European Space Agency's Huygens probe to parachute to Titan's 
surface.  The probe's scientific instruments would study 
Titan's atmosphere and surface, which are thought to share key 
characteristics with Earth's early environment before life 
began.  The international mission would result in the most 
complete characterization ever undertaken of a planetary system 
beyond Earth and the Moon.  The Jet Propulsion Laboratory in 
Pasadena, CA, manages the Cassini project for NASA.

     Electrical power to operate the Cassini spacecraft systems 
would be provided by three radioisotope thermoelectric 
generators (RTGs).  Such generators have been used on 23 
previous U.S. space missions, including the Apollo lunar 
landings, the Voyager flybys of Jupiter, Saturn, Uranus and 
Neptune, the Pioneer missions to Jupiter and Saturn, the 
Galileo mission to Jupiter and the Ulysses solar mission.  

     The Cassini RTGs, provided to NASA by the U.S. Department of 
Energy, produce electricity from the heat emitted by a non-
weapons grade isotope of plutonium.  Spacecraft power source 
options have been extensively evaluated for the Cassini mission 
and are discussed in the DEIS.  Detailed analysis showed that 
RTGs are the only reliable technology, presently available and 
tested for use in space, that can meet the spacecraft's power 
needs for traveling to Saturn and accomplishing the mission's 
scientific objectives.

     Analysis provided in the DEIS found that the likely 
environmental impacts of the mission are limited to those 
associated with the normal launch of the Titan IV/Centaur 
launch vehicle.  Furthermore, it indicated that the overall 
risks associated with the mission are low.  Representative 
launch accident scenarios were evaluated for the planned 
mission and mission alternatives.  Extensive Department of 
Energy testing and evaluation programs have demonstrated the 
effectiveness of RTGs in containing their plutonium under a 
wide range of accident conditions.  In the unlikely case of a 
launch accident that resulted in the release of plutonium, the 
risk to public health is assessed to be negligible.  

     In the even less likely event of an inadvertent atmospheric 
reentry of Cassini during its Earth swingby, there is a small 
potential for public health effects, according to studies 
reported in the DEIS.  However, NASA is designing the 
spacecraft and mission to ensure that the probability of an 
Earth reentry, after the spacecraft has left Earth orbit, is 
less than one in one million.

                     -more-     

                      -3-

     The Cassini DEIS is available for public review at each NASA 
Center.  For more information on the DEIS or the Cassini 
mission, contact Dr. Peter B. Ulrich, Chief of Flight Programs 
in the Office of Space Science at NASA  Headquarters, Code SL, 
Washington, DC, 20546.

                      - end-

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