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Planning and Quick Improvisation
Succeed in Space Biz
On December 18, 2001, ground controllers at JPL commanded NASA's Deep
Space 1 (DS1) spacecraft to go to sleep. "It was a
bittersweet moment," recalls Marc Rayman, the DS1 project
manager. Everyone was exhausted, including Deep Space 1, which for
three years had taken Rayman and his team on the ride of their
DS1 blasted off atop a Delta rocket in 1998. Most spacecraft are
built from tried-and-true technology-otherwise mission controllers
won't let them off the ground. But Deep Space 1 was different.
Its mission was to test 12 advanced technologies. Among them: an
experimental ion engine, a solar array that focused sunlight for extra
power, and an autopilot with artificial intelligence. "There was a
good chance DS1 wouldn't work at all; there were so many untried
systems," recalls Rayman.
Nevertheless, all 12 technologies worked; the mission was a big
Indeed, DS1 worked so well that in 1999 NASA approved an extended
mission, which Rayman and colleagues had dreamed up long before DS1
left Earth-a visit to a comet. "We were thrilled," says
And that's when disaster struck. DS1's orientation system failed.
The spacecraft couldn't navigate!
What do you do when a spacecraft breaks and it is 200 million miles
away? "Improvise," says Rayman.
Ironically, the device that broke, the 'Star Tracker,' was old
technology. The DS1 team decided to use one of the 12
experimental devices-a miniature camera called MICAS-as a
substitute. With Comet Borrelly receding fast, they reprogrammed
the spacecraft and taught it to use MICAS for navigation, finishing
barely in time to catch the comet. "It was a very close
In September 2001, DS1 swooped past the furiously evaporating nucleus
of Comet Borrelly. "We thought the spacecraft might be
pulverized," Rayman recalls, but once again DS1 defied the odds.
It captured the best-ever view of a comet's heart and emerged
By that time, DS1 had been operating three times longer than planned,
and it had nearly exhausted its supply of thruster-gas used to keep
solar arrays pointed toward the Sun. Controllers had no choice but to
deactivate the spacecraft, which remains in orbit between Earth and
Rayman has moved on to a new project-Dawn, an ion-propelled
spacecraft that will visit two enormous asteroids, Ceres and Vesta, in
2010 and 2014. "Dawn is based on technologies that DS1
pioneered," he says.
Even asleep, DS1 continues to amaze.
Find out more about DS1 at http://nmp.jpl.nasa.gov/ds1 . For
kids, go to http://spaceplace.nasa.gov/ds1dots.htm to do an
interactive dot-to-dot drawing of Deep Space 1.
This was the final image of the nucleus of comet Borrelly, taken
just 160 seconds before Deep Space 1's closest approach to it. This
image shows the 8-km (5-mile) long nucleus from about 3417 kilometers
(over 2,000 miles) away.
This article was provided by the Jet Propulsion Laboratory,
California Institute of Technology, under a contract with the National
Aeronautics and Space Administration.
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