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Stardust return preview
NASA's Stardust spacecraft encountered Comet Wild 2 two years ago, gathering samples of cometary dust for return to Earth. In this Dec. 21 news conference, mission officials and scientists detail the probe's homecoming and planned landing in Utah scheduled for January 15, 2006.

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Science of New Horizons
The first robotic space mission to visit the distant planet Pluto and frozen objects in the Kuiper Belt is explained by the project's managers and scientists in this NASA news conference from the agency's Washington headquarters on Dec. 19.

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Shuttle program update
Bill Gerstenmaier, NASA associate administrator for space operations, discusses the latest space shuttle program news, including the decision to remove the PAL foam ramp from future external fuel tanks, during this December 15 teleconference with reporters.

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Remembering Gemini 6
The Gemini 6 mission launched from the Cape at 8:37 a.m. December 15, 1965 to rendezvous with the orbiting Gemini 7 spacecraft. The rendezvous occurred and Gemini 6 safely returned to Earth.

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New views of icy moons
NASA's Cassini spacecraft orbiting Saturn is wrapping up a phenomenally successful year of observing the mysterious icy moons, including Enceladus, Dione, Rhea, Hyperion and Iapetus.

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First ISS spacewalkers
Mission Control remembers the spacewalking efforts by astronaut Jerry Ross and Jim Newman from this week in 1998. The duo worked to connect the first two pieces of the International Space Station -- the Russian-made Zarya control module and the U.S Unity node.

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Mars rover panoramas
New panoramas from NASA's long-lasting Mars Exploration Rovers show the view from the Columbia Hills where Spirit continues its adventure and the strange landscape at Meridiani Planum where Opportunity is driving southward.

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Hubble Space Telescope
Scientists marvel at the achievements made by the orbiting Hubble Space Telescope in this produced movie looking at the crown jewel observatory that has served as our window on the universe.

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NASA astronomers spot rare lunar meteor strike
NASA-MSFC NEWS RELEASE
Posted: December 23, 2005

Astronomers at NASA's Marshall Space Flight Center, Huntsville, Ala., have recorded a small but powerful meteoroid strike in the night on the moon's surface.


This artist's rendering of a small but powerful meteor strike on the surface of the moon demonstrates a key concern for future lunar explorers -- mitigating potential risks from impact "ejecta," or the spray of debris that follows an impact, unimpeded by gravity or atmosphere. Credit: NASA/MSFC
 
On Nov. 7, using a 10-inch-diameter telescope, astronomers recorded a tiny blip northwest of Mare Imbrium, the moon's "Sea of Showers." Such impacts are not uncommon, but it was only in 1999 that scientists first recorded a lunar strike as it happened.

"People just do not look at the moon anymore," said Dr. Robert Suggs, Space Environment team lead in the Natural Environments Branch of the Marshall Center's Engineering Directorate. "We tend to think of it as a known quantity. But there is knowledge still to be gained here."

As NASA plans to return to the moon, the agency has a need to understand what happens after lunar impacts in order to protect lunar explorers. On Earth, the atmosphere vaporizes most small meteoroids, leaving nothing behind but a brief streak of light. The vacuum environment on the moon, however, means there is nothing to slow incoming meteoroids before they strike.

"The likelihood of being struck by a meteoroid on the lunar surface is very, very small," said Bill Cooke, an astronomer in Marshall's Meteoroid Environment Office. "The challenge is learning what happens to high-velocity ejecta, the debris kicked up by a meteoroid strike, which is not hindered by atmospheric friction or Earth gravity. What threat does that debris pose to humans or equipment?"

Suggs, who heads the impact study, used commercial software tools to study the video frame by frame, and spotted a very bright flash. The burst of light diminished gradually over the course of five video frames, each 1/30th of a second in duration. Suggs called in Cooke, and both scientists agreed that the bright light was an impact flash, captured by video from some 248,000 miles away.

Immediately, the team began ruling out other possible causes. Two telling characteristics won out -- the gradual diminishment of the flash rather than an on-off "winking" effect, and its motionlessness. A flicker of light from a moving satellite, Cooke noted, would have appeared to shift perceptibly, even in five brief frames of video.

Suggs and Cooke next consulted star charts and lunar imaging software and determined the meteoroid was likely a Taurid, part of an annual meteor shower active at the time of the strike. Based on the amount of light produced the object was roughly five inches in diameter, traveling more than 60,000 mph, and may have gouged a crater nearly 10 feet in diameter out of the moon's surface.

The Taurids, which approach Earth from the direction of the Taurus constellation, are believed to be ancient remnants of comet Encke, which orbits the Sun every 3.3 years.

NASA scientists previously studied lunar meteor strikes during the Apollo moon program, but lacked the sophisticated video cameras and high-powered image processors to capture the tiny, telling flashes. Now, however, as NASA readies its next-generation spaceship to carry explorers back to the moon for potential long-term stays, Suggs and Cooke say lunar impact research is more vital than ever.

"Large-scale lunar facilities are sure to be well-protected, using impact-resistant technologies much like those developed to shield the space shuttle and the International Space Station," Suggs said. "We want to support additional measures that safeguard personnel working in the lunar field -- early-alert systems, emergency protective measures and new technologies that will mitigate risks from flying impact debris."