ARG%SU-AI@sri-unix.UUCP (02/29/84)
From: Ron Goldman <ARG@SU-AI>
n029 1006 29 Feb 84
BC-SCIENCE-WATCH (UNDATED)
(ScienceTimes)
c. 1984 N.Y. Times News Service
A team of 20 American and European astronomers has chosen a bright,
short-period comet named Kopff as target for a mission to intercept
the comet, fly around it at a range of six miles and then sail along
with it at a greater distance as it approaches the sun.
The spacecraft, a projected design of the Jet Propulsion Laboratory
known as the Mariner Mark II, would be launched in 1990 to meet the
comet four years later. It would be the third comet to become target
of intercept missions but the first to be joined in its orbit by the
probe.
The International Cometary Explorer of the National Aeronautics and
Space Administration has been aimed to fly past the comet
Giacobini-Zinner next year. In 1986 European, Japanese and Soviet
spacecraft are scheduled to rendezvous with Halleys Comet. But these
are ''fly-by'' missions in which the spacecraft have only one look at
their target.
Comet Kopff was chosen by a committee convened for that purpose by
NASA at the California Institute of Technology. According to the Jet
Propulsion Laboratory, which is operated by Cal Tech, the spacecraft
is expected to remain with the comet for several years, observing its
response to the effects of sunlight and other forms of solar
radiation as it approaches and loops around the sun.
Unlike most comets, whose orbits around the sun are measured in
decades, centuries or millenia, this one circles the sun every 6.5
years. The rendezvous would be performed two years before the comet
makes its closest approach to the sun.
After making observations while orbiting a few miles from the comet
the craft would be commanded to move to a greater distance as the
comet, under the influence of increasingly intense solar heat and
radiation, develops a cloudy envelope, or coma, and a tail.
Such is the timing of the mission that it would allow the spacecraft
to take ''close looks'' at two asteroids, Namaqua and Lucia, while en
route to the rendezvous.
The Mariner Mark II is envisioned as a ''bargain basement''
spacecraft, using electronics and other components from existing (and
more elaborate) models, such as the Vikings that went to Mars and
probes to the other planets - Voyagers, Galileo and the Venus Radar
Mapper.
Other targets for the Mark II design could include the Saturnian
moon Titan, the outer planet Uranus and the asteroids that orbit the
sun in a zone between the orbits of Mars and Jupiter.
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