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Deep Impact comet mission producing surprises NASA NEWS RELEASE Posted: September 6, 2005 Painting by the numbers is a good description of how scientists create pictures of everything from atoms in our bodies to asteroids and comets in our solar system. Researchers involved in NASA's Deep Impact mission have been doing this kind of work since the mission's July 4th collision with comet Tempel 1.
For example, comet Tempel 1 has a very fluffy structure that is weaker than a bank of powder snow. The fine dust of the comet is held together by gravity. However, that gravity is so weak, if you could stand on the bank and jump, you would launch yourself into space. Another surprise for A'Hearn and his colleagues was the evidence of what appears to be impact craters on the surface of the comet. Previously two other comets had their nuclei closely observed, and neither showed evidence of impact craters. "The nucleus of Tempel 1 has distinct layers shown in topographic relief ranging from very smooth areas to areas with features that satisfy all the criteria for impact craters, including varying size," A'Hearn said. "The problem in stating with certainty that these are impact craters is that we don't know of a mechanism by which some comets would collide with the flotsam and jetsam in our solar system, while others would not," he added. According to A'Hearn, one of the more interesting findings may be the huge increase in carbon-containing molecules detected in spectral analysis of the ejection plume. This finding indicates comets contain a substantial amount of organic material, so they could have brought such material to Earth early in the planet's history when strikes by asteroids and meteors were common. Another finding is the comet interior is well shielded from the solar heating experienced by the surface of the comet nucleus. Mission data indicates the nucleus of Tempel 1 is extremely porous. Its porosity allows the surface of the nucleus to heat up and cool down almost instantly in response to sunlight. This suggests heat is not easily conducted to the interior and the ice and other material deep inside the nucleus may be pristine and unchanged from the early days of the solar system, just as many scientists had suggested. "The infrared spectrometer gave us the first temperature map of a comet, allowing us to measure the surface's thermal inertia, or ability to conduct heat to the interior," said Olivier Groussin, the University of Maryland research scientist who generated the map. It is this diligent and time consuming analysis of spectral data that is providing much of the "color" with which Deep Impact scientists are painting the first ever detailed picture of a comet. For example, researchers recently saw emission bands for water vaporized by the heat of the impact, followed a few seconds later by absorption bands from ice particles ejected from below the surface and not melted or vaporized. "In a couple of seconds the fast, hot moving plume containing water vapor left the view of the spectrometer, and we are suddenly seeing the excavation of sub-surface ice and dust," said Deep Impact co-investigator Jessica Sunshine, with Science Applications International Corporation, Chantilly, Va. "It is the most dramatic spectral change I've ever seen." These findings were published in the September 9 issue of the journal Science, and presented at the Division for Planetary Sciences meeting in Cambridge, England. Mission scientists are filling in important new portions of a cometary picture that is still far from finished.
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The Mars Exploration Rover Spirit has reached the summit of Husband Hill, returning a spectacular panorama from the hilltop in the vast Gusev Crater. Scientists held a news conference Sept. 1 to reveal the panorama and give an update on the twin rover mission.
To gain a new perspective on space shuttle Discovery's ascent and gather additional imagery for the return to flight mission, NASA dispatched a pair of high-flying WB-57 aircraft equipped with sharp video cameras in their noses.
When space shuttle Discovery launched its two solid-fuel booster rockets were equipped with video cameras, providing dazzling footage of separation from the external fuel tank, their free fall and splashdown in the sea.
Mounted atop a modified Boeing 747, space shuttle Discovery was ferried across the country from Edwards Air Force Base, California, to Kennedy Space Center, Florida.
Shuttle fuel tank ET-119 is loaded onto a barge at Kennedy Space Center for the trip back to Lockheed Martin's Michoud Assembly Facility in New Orleans. The tank will be used in the investigation to determine why foam peeled away from Discovery's tank on STS-114 in July.
Launch of the GOES-N weather observatory aboard a Boeing Delta 4 rocket is postponed at Cape Canaveral, Florida.
The Mars Reconnaissance Orbiter lifts off aboard a Lockheed Martin Atlas 5 rocket from Cape Canaveral's Complex 41.
Explosives topple the abandoned Complex 13 mobile service tower at Cape Canaveral Air Force Station. This video was shot from the blockhouse roof at neighboring Complex 14 where John Glenn was launched in 1962.
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