PASADENA, Calif., Dec. 9 (UPI) -- A NASA science probe Monday finished its work collecting interstellar dust grains for return to Earth on the heels of a successful dress rehearsal for its comet rendezvous mission.
The minuscule particles -- each no bigger than a micron, or a millionth of a meter -- have been captured by the Stardust spacecraft, which is just more than a year from its primary mission to study and collect samples from a comet.
"More and more things are behind us now, so we're feeling pretty good about the mission," Stardust principal scientist Donald Brownlee, with the University of Washington in Seattle, said in an interview with United Press International.
Ground control teams at NASA's Jet Propulsion Laboratory watched over the spacecraft as it delicately retracted its tennis racket-like wand, which is filled with a substance called aerogel that traps and preserves the fast-moving celestial specks of dust.
One side of the wand contains interstellar dust grains taken during two periods since the probe's launch in 1999. The other side is being reserved for samples from Comet Wild-2 (pronounced "vilt-2"). The comet encounter is planned for January 2004.
The spacecraft will be in an orientation one more time to collect more dust grains before the comet encounter, but Brownlee said the team decided to pass up the third collection period and focus instead on preparing for the one-shot comet flyby.
If all goes as planned, Stardust will return to Earth in 2006 and jettison a capsule containing its precious samples that will parachute to Earth. Among the studies scientists plan is a comparison between the interstellar dust -- which is blown into our solar system by other stars in the galaxy -- and the comet particles, which are thought to be relics from the original dust cloud from which our solar system was formed.
"From the dust grains, we're hoping that we can learn something about how elements heavier than hydrogen and helium are formed by stars," said Brownlee. "We know that different stars do that in different ways, but we don't know how."
Stardust last month flew by an asteroid to test its equipment and operating procedures for the comet rendezvous.
"That was just a little teaser of what's going to come," said Brownlee.
NASA also said it is delaying launch of its dust-peering infrared space telescope from January to April 2003. A launch pad accident at Cape Canaveral Air Force Station in late October was the primary trigger for the delay, said Jet Propulsion Laboratory spokeswoman Jane Platt.
However, a problem with a valve on the telescope's steering system also is taking some time to resolve. NASA is retargeting launch of the long-delayed Space Infrared Telescope Facility to no earlier than April 15. If the observatory cannot be launched by mid-May, however, it will face another lengthy delay as NASA will shift its focus to launching two Mars probes during the critical time that Earth and Mars are favorably aligned.
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(Reported by Irene Brown, UPI Science News, at Cape Canaveral, Fla.)
