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NASA Science Highlight: Planetary Program Support
Research by Ashwin Vasavada, B T Greenhagen, NASA's Jet Propulsion Laboratory; D A Paige, M A Siegler, J Williams, UCLA; JL Bandfield, University of Washington
Science Writer, Samantha Harvey
On January 15, 2006, the Stardust spacecraft completed one history-making mission and began another. Returning from a rendezvous with Comet Wild 2, the spacecraft approached Earth and jettisoned the capsule containing particles collected directly from the comet, as well as the interstellar dust medium. The capsule landed safely and on-target southwest of Salt Lake City, Utah, completing the world's first sample return from a comet. Then, on February 14, 2011, the spacecraft, on its second mission of exploration called Stardust-NExT, visited Comet Tempel 1-- the comet previously targeted by the Deep Impact mission, making it the first-ever follow-up mission to a comet.
The spacecraft made its closest approach to Comet Tempel 1 on Monday, Feb. 14, at 8:40 p.m. PST (11:40 p.m. EST) at a distance of approximately 178 kilometers (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 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.
Several of the images provide clues to the result of the Deep Impact mission's collision with Tempel 1.
Observations included a crater with a small mound in the center, indicating that some of the ejecta from Deep Impact went up and came right back down, meaning that the cometary nucleus is fragile and weak, with particles exploding from the surface in large chunks that crumbled, rather than a little stream of uniform particles ejecting from the impact crater.
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.
Implications:
The Stardust-NExT mission contributes greatly to understanding comets by capitalizing on missions such as Deep Impact to determine how cometary nuclei were constructed at the birth of the solar system and increase our understanding of how they have evolved since then. The mission also provides NASA with the unique opportunity to study two entirely different comets with the same instrument. By doing this scientists will be able to more accurately compare its existing data set.
Significance to Solar System Exploration:
Comets offer clues to the composition and processes that formed the giant planets in the outer solar system. For example, some of the particles gleaned from the Stardust mission were formed at very high temperatures near the sun and yet comets formed in the cold outer regions of our solar system so there was apparently significant material flows from the inner to the outer solar system during its formation process.
Last Updated: 27 June 2012
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