Comet rendezvous “100% successful”

Four different Stardust views of Tempel 1

Four different views of comet Tempel 1 as seen by NASA's Stardust spacecraft as it flew by on Feb. 14, 2011. The images progress in time beginning at upper left, moving to upper right, then proceeding from lower left to lower right. The upper right and lower left images are the best ones, taken at 3 seconds before, and 3 seconds after, the closest approach.

NASA’S STARDUST SPACECRAFT returned new images of a comet showing a scar resulting from the 2005 Deep Impact mission. The images also showed that the comet has a fragile and weak core or nucleus.

The spacecraft made its closest approach to comet Tempel 1 on Tuesday, February 15 at 3:40pm Sydney time (Monday, Feb. 14 at 8:40pm US PST or 11:40pm US EST) at a distance of approximately 178 kilometres (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.”

Location of the impact by the impactor from the Deep Impact

Close up of the location hit by the impactor from the Deep Impact spacecraft back in 2005.

Before-and-after comparison of part of Tempel 1

This pair of images shows the before-and-after comparison of the part of comet Tempel 1 that was hit by the impactor from NASA's Deep Impact spacecraft back in 2005.

Like flying through WWII flak

Several of the images provide tantalising clues to the result of the Deep Impact mission’s collision with Tempel 1.

“We see a crater with a small mound in the centre, and it appears that some of the ejecta went up and came right back down,” said Pete Schultz of Brown University. “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.”

Changes in the surface of Tempel 1

This image layout depicts changes in the surface of comet Tempel 1, observed first by NASA's Deep Impact Mission in 2005 (top) and again by NASA's Stardust-NExT mission on February 14, 2011 (bottom).

Mission almost over

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 [5.6 billion kilometres] 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.”

Stardust-NExT is a low-cost mission that is expanding the investigation of comet Tempel 1 initiated by the Deep Impact spacecraft. The mission is managed by JPL for NASA’s Science Mission Directorate in Washington. Lockheed Martin Space Systems in Denver built the spacecraft and manages day-to-day mission operations.

Adapted from information issued by NASA JPL. Images courtesy NASA / JPL-Caltech / University of Maryland / Cornell.

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