[meteorite-list] Deep Space 1 Loads Up For Trek To Comet

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 09:44:41 2004
Message-ID: <200103210234.SAA25724_at_zagami.jpl.nasa.gov>

PASADENA, CALIF. 91109 TELEPHONE (818) 354-5011

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



       NASA's Deep Space 1 spacecraft, sailing through the solar system
today, has taken delivery of a new cargo: the latest software for its
ambitious encounter with Comet Borrelly this September.

       After successfully finishing its primary mission in 1999 as a testing
ground for important new technologies, NASA approved a risky bonus mission
to Comet Borrelly for Deep Space 1. There the spacecraft will take
black-and-white pictures, use infrared pictures to find out the nature of
the comet's surface, measure and identify the gases coming from the comet,
and measure the interaction of solar wind with the comet. To take pictures
of the comet, Deep Space 1 must upgrade its software's pointing system to
turn the spacecraft from a testbed for advanced technologies to a chronicler
of Comet Borrelly.

       "Deep Space 1's previous version of software, which was transmitted
to the spacecraft nine months ago, has proven itself during the surprisingly
successful flight through the solar system since then, but now we're giving
the probe a new assignment," said Dr. Marc Rayman, the project manager. "And
in order to prepare for this exciting and daring comet encounter, the
software needs to be upgraded."

       The spacecraft team will be checking the software, radioed to Deep
Space 1 throughout the week of March 5. The first check came when the team
actually received a signal from the spacecraft after it shut the main
computer off and restarted it. Since the software sent by the team works
well, the spacecraft sent a signal indicating it is healthy. Now engineers
are giving the spacecraft's new software a thorough physical checkup.

       "The process of transmitting the new software to the spacecraft,
rebooting the on-board computer to begin running it, verifying that the
spacecraft is working properly with the new software and restoring the craft
to its cruise configuration, all when the spacecraft is 318 million
kilometers (197 million miles) away, is a complex and tricky operation, "
said Daniel Eldred, the Deep Space 1 mission manager.

       The new software contains capabilities that will be needed when the
spacecraft gets to Borrelly. The new commands will include lessons that Deep
Space 1 learned in its 1999 encounter with asteroid Braille about the
behavior of the spacecraft when it gets close to a solar system object.

       The spacecraft carries a device, part of the successful new
technology system, which holds two cameras. One uses a conventional
charge-coupled device detector, the other a new technology detector. The
test camera, though performing its initial tests successfully, wasn't
equipped to deal with the very dark object that Braille turned out to be.
Small bodies like asteroids and comets are still a mystery. Since they're so
small and distant, their exact size and shape can't usually be determined
from Earth. Deep Space 1 plans to use its tried- and-true CCD camera to try
to snap photos of Borrelly. The team will send commands to the new software
to stop using the test camera and start using the CCD camera, which will
take a larger picture with more light.

       In late 1999, after the successful end of its primary mission, Deep
Space 1 lost its star tracker, and the spacecraft had to be reconfigured to
use the photographic camera to orient itself by the stars around it. In
order to take pictures of Borrelly, the camera can't align the spacecraft
and snap photos of the comet at the same time. Instead, the spacecraft will
have to rely on its fiber-optic gyroscopes to help maintain its orientation.
But the gyros are not accurate enough by themselves, so the new software
will try to correct for those inaccuracies. The new software is designed to
help the camera stay pointed at the comet's nucleus during the 15 minutes
that the camera will attempt to observe the comet.

       Deep Space 1 was launched in October 1998 as part of NASA's New
Millennium Program, which is managed by JPL for NASA's Office of Space
Science, Washington, D.C. The California Institute of Technology in Pasadena
manages JPL for NASA.

       Deep Space 1 completed its primary mission testing ion propulsion and
11 other advanced technologies in September 1999. NASA extended the mission,
taking advantage of the ion propulsion and other systems to target a chancy
but exciting encounter with the comet in September 2001. More information
can be found on the Deep Space 1 Home Page at http://nmp.jpl.nasa.gov/ds1/ .

Received on Tue 20 Mar 2001 09:34:31 PM PST

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