MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109 TELEPHONE (818) 354-5011
Contact: John G. Watson
FOR IMMEDIATE RELEASEJuly 29, 1999
NASA'S DEEP SPACE 1 SUCCEEDS IN CLOSE ASTEROID FLYBY
NASA's Deep Space 1 experimental spacecraft successfully
flew closely above the surface of asteroid 9969 Braille at 9:46
p.m. Pacific time Wednesday, July 28 (04:46 Universal Time July
29), using a sophisticated new space autopilot system, exceeding
100 percent of the mission's objectives.
An exultant operations team looked on as preliminary data
returned to the Deep Space 1 operations control area at NASA's
Jet Propulsion Laboratory, Pasadena, CA, indicating that the
AutoNav autopilot system skillfully flew the spacecraft to a
face-to-face closeup with asteroid Braille.
"This is a dramatic finale to an amazingly successful
mission," said Dr. Marc Rayman, chief mission engineer and deputy
mission manager. "With AutoNav's successful piloting of the
spacecraft, we've completed the testing and validation of the 12
new technologies onboard and possibly acquired important science
data, including photos."
Data from the spacecraft will be analyzed in coming days to
determine the actual flyby distance, which at about 15 kilometers
(less than 10 miles), was by far the closest flyby of an asteroid
Ten minutes after the flyby, when the spacecraft signals
reached Earth after a 10-minute journey, the team burst into
spontaneous applause at the news that the spacecraft was turning
back to face the asteroid. The turn was indicated by a marked
Doppler shift, a clear early indicator of a successful encounter.
Like a siren whose pitch changes after passing by, the Doppler
shift indicates movement past an object.
Launched Oct. 24, 1998, Deep Space 1 is the first mission
under NASA's New Millennium Program, which tests new technologies
for future space and Earth-observing missions. The technologies
that have been tested on Deep Space 1 will help make future
science spacecraft smaller, less expensive, more autonomous and
capable of more independent decision-making so that they rely
less on tracking and intervention by ground controllers.
Of the 12 new technologies on board, all but the
spacecraft's autonomous navigation system had been completely
tested since launch. With the asteroid encounter, AutoNav
finished its last five percent of testing.
Making the flyby all the more memorable -- and serving as a
testimonial to the team's quick ability to think on its feet --
was the fact that the spacecraft experienced a "safing" event
earlier in the day, starting at about 5 a.m. PDT on July 28 and
ending at about 11 a.m. PDT. A small software glitch, now fully
diagnosed, was detected by Deep Space 1's fault-detection
software, which triggered a protective program that causes
several events: the spacecraft halts non-critical activity,
orients its solar panels toward the Sun, points light and heat-
sensitive instruments away from the Sun and reverts to its low-
gain antenna while awaiting new commands.
"This has been by far the most challenging, dramatic and
stressful day on the project," said Rayman. "The last 16 hours
before the flyby were really, really exciting. We had the safing
event, we recovered from it and we managed to squeeze in a
trajectory correction maneuver to update Deep Space 1's flight
Science results will be downlinked in a series of telemetry
sessions over the next several days. During the flyby, a
spectrometer and imaging instrument took black-and-white
photographs and images taken in infrared light, while a second
instrument observed the three-dimensional distribution of ions
and electrons, or plasma, in the area.
A science update covering science results is scheduled to
take place at NASA's Jet Propulsion Laboratory, Pasadena, Calif.,
on Tuesday, August 3, at 10 a.m. PDT. It will be broadcast live
on NASA TV.
A Deep Space 1 asteroid flyby press kit, along with mission
status reports from launch to the present, is available at
http://www.jpl.nasa.gov/ds1news . A live videocam view of the Deep Space
1 mission control area is available at go to http://eis/~mbareh/MSA.html .
Deep Space 1 is budgeted at $152 million, including design,
development, launch and operations. The mission is managed for
NASA's Office of Space Science by JPL, a division of the
California Institute of Technology. JPL is a division of the California Institute of Technology,