[meteorite-list] JPL Navigators Drive Two-For-One Comet Mission

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:00:04 2004
Message-ID: <200207012205.PAA05116_at_zagami.jpl.nasa.gov>

MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109 TELEPHONE (818) 354-5011
http://www.jpl.nasa.gov

Contact: Martha J. Heil (818) 354-0850

FOR IMMEDIATE RELEASE July 1, 2002

JPL NAVIGATORS DRIVE TWO-FOR-ONE COMET MISSION

     NASA's Comet Nucleus Tour, slated to launch no earlier than July 3, will
rely on the Jet Propulsion Laboratory's navigation experts to guide the
craft on its tricky journey toward two comets to find out how the icy, rocky
bodies evolve as they approach the Sun.

     The spacecraft is slated for a 15-month journey to Comet Encke followed by
a two-and-a-half-year trip to Comet Schwassmann-Wachmann 3. The mission was
conceived so that scientists could compare the older, less active Encke to
the younger, dust-clouded Schwassmann-Wachmann 3. The different targets pose
a challenge to the navigators, too.

     "We'll be flying by quickly and close to Comet Encke. There will be just
ten minutes of time to take the science data, and our job is to protect that
time," said Tony Taylor, chief of the navigation team at JPL, in Pasadena,
Calif. "On the other hand, Comet Schwassman-Wachmann 3 has more dust and gas
shooting from its inner body. We will fly past it a bit farther away to avoid
being hit by a particularly large particle, and we'll have more time to observe
the comet."

     The navigation team will guide the spacecraft through its complex orbit.
The cleverly developed launch plan will first send the spacecraft into an
Earth-circling orbit. After six weeks, the navigators will steer the spacecraft
toward the first of the two comets.

     "It's like having two launches," said Dr. Bobby Williams, a member of the
navigation team and the leader of the JPL navigation team that landed the Near
Earth Asteroid Rendezvous spacecraft on the asteroid Eros in February 2001.
"We have to fire a rocket to go into orbit around Earth and then about six
weeks later fire another rocket to push the spacecraft out of Earth orbit."

     The spacecraft will fly by each comet at the peak of its activity as it
approaches the Sun. During each encounter, the target comet will be well
situated in the night sky for astronomers worldwide to make concurrent
observations from the ground. Protected by its dust shield, the spacecraft
will fly by each comet nucleus to within a distance of 100 kilometers
(62 miles). The most intensive data taking will occur within a day or so of
each encounter.

     The mission's design is flexible so that the spacecraft can be retargeted
to intercept an unexpected comet visitor. If a "new" comet passes close enough
to Earth's orbit, mission managers at the Johns Hopkins University Applied
Physics Laboratory, Laurel, Md., will design a new flight path to take
advantage of the opportunity to study the new comet. The JPL navigation team
will then calculate the amount of fuel the spacecraft should burn, and for how
long, to put it on the right path.

     JPL will also provide communications support through the Deep Space
Network, the worldwide series of antennas that provide radio communications for
all of NASA's interplanetary spacecraft.

     "JPL's participation is essential to making the mission happen," said Dr.
Joseph Veverka, principal investigator and leader of the mission from Cornell
University, Ithaca, N.Y. "We have to get the spacecraft very close to the
comets and we have to communicate with the spacecraft – and we couldn't do
those things without JPL. And one of the world's experts on comets, Dr. Don
Yeomans of JPL, is part of our science team."

     Comets may have brought to the forming Earth some of the water in the
oceans, some of the gases of our atmosphere and perhaps even the building
blocks from which life arose.

     JPL is managed for NASA by the California Institute of Technology,
Pasadena, Calif. The Johns Hopkins University Applied Physics Laboratory
manages the mission, built the spacecraft and its two cameras and will
operate the spacecraft during flight. NASA's Goddard Space Flight Center,
Greenbelt, Md., provided the spacecraft's neutral gas/ion mass spectrometer.
Von Hoerner & Sulger, GmbH, Schwetzingen, Germany, built the dust analyzer.
Veverka leads a science team of 18 co-investigators from universities,
industry and government agencies in the United States and Europe. More
information on the mission is available at

http://www.contour2002.org .

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Received on Mon 01 Jul 2002 06:05:20 PM PDT