Flyby Reveals Scar From Deep Impact Mission
NASA's Stardust spacecraft returned new images of a comet
showing a scar resulting from the 2005 Deep Impact mission. The
images also showed the comet has a fragile and weak nucleus.
Comet Tempel 1 NASA Image
The spacecraft made its closest approach to comet Tempel 1 on
Monday, Feb. 14, at 2040 PST at a distance of approximately 111
miles. Stardust took 72 high-resolution images of the comet. It
also accumulated 468 kilobytes of data about the dust in its coma,
the cloud that is a comet's atmosphere. The craft is on its second
mission of exploration called Stardust-NExT, having completed its
prime mission collecting cometary particles and returning them to
Earth in 2006.
The Stardust-NExT mission met its goals which included observing
surface features that changed in areas previously seen during the
2005 Deep Impact mission; imaging new terrain; and viewing the
crater generated when the 2005 mission propelled an impactor at the
comet. "This mission is 100 percent successful," said Joe Veverka,
Stardust-NExT principal investigator of Cornell University, Ithaca,
N.Y. "We saw a lot of new things that we didn't expect, and we'll
be working hard to figure out what Tempel 1 is trying to tell
us."
NASA Image
Several of the images provide tantalizing clues to the result of
the Deep Impact mission's collision with Tempel 1. "We see a crater
with a small mound in the center, and it appears that some of the
ejecta went up and came right back down," said Pete Schultz of
Brown University, Providence, R.I. "This tells us this cometary
nucleus is fragile and weak based on how subdued the crater is we
see today."
Engineering telemetry downlinked after closest approach
indicates the spacecraft flew through waves of disintegrating
cometary particles including a dozen impacts that penetrated more
than one layer of its protective shielding. "The data indicate
Stardust went through something similar to a B-17 bomber flying
through flak in World War II," said Don Brownlee, Stardust-NExT
co-investigator from the University of Washington in Seattle.
"Instead of having a little stream of uniform particles coming out,
they apparently came out in chunks and crumbled."
NASA Image
While the Valentine's Day night encounter of Tempel 1 is
complete, the spacecraft will continue to look at its latest
cometary obsession from afar. "This spacecraft has logged over 3.5
billion miles since launch, and while its last close encounter is
complete, its mission of discovery is not," said Tim Larson,
Stardust-NExT project manager at JPL. "We'll continue imaging the
comet as long as the science team can gain useful information, and
then Stardust will get its well-deserved rest."