[meteorite-list] I Love Comets

[Meteorites USA]

Flyby Time. Happy Valentine NExT
http://www.jpl.nasa.gov/news/news.cfm?release=2011-050&cid=release_2011-050&msource=11050&tr=y&auid=7771872

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NASA Spacecraft Hours From Comet Encounter
February 14, 2011
Stardust-Next Mission Status

PASADENA, Calif. -- As of today, Feb. 14, at 9:21 a.m. PST (12:21 p.m. 
EST), NASA's Stardust-NExT mission spacecraft is within a 
quarter-million miles (402,336 kilometers) of its quarry, comet Tempel 
1, which it will fly by tonight. The spacecraft is cutting the distance 
with the comet at a rate of about 10.9 kilometers per second (6.77 miles 
per second or 24,000 mph).

The flyby of Tempel 1 will give scientists an opportunity to look for 
changes on the comet's surface since it was visited by NASA's Deep 
Impact spacecraft in July 2005. Since then, Tempel 1 has completed one 
orbit of the sun, and scientists are looking forward to discovering any 
differences in the comet.

The closest approach is expected tonight at approximately 8:40 p.m. PST 
(11:40 p.m. EST).

During the encounter phase, the spacecraft will carry out many important 
milestones in short order and automatically, as the spacecraft is too 
far away to receive timely updates from Earth. These milestones include 
turning the spacecraft to point its protective shields between it and 
the anticipated direction from which cometary particles would approach. 
Another milestone will occur at about four minutes to closest approach, 
when the spacecraft will begin science imaging of the comet's nucleus.

The nominal imaging sequence will run for about eight minutes. The 
spacecraft's onboard memory is limited to 72 high-resolution images, so 
the imaging will be most closely spaced around the time of closest 
approach for best-resolution coverage of Tempel 1's nucleus. At the time 
of closest encounter, the spacecraft is expected to be approximately 200 
kilometers (124 miles) from the comet's nucleus.

The mission team expects to begin receiving images on the ground 
starting at around midnight PST (3 a.m. on Feb. 15 EST). Transmission of 
each image will take about 15 minutes. It will take about 10 hours to 
complete the transmission of all images and science data aboard the 
spacecraft.

Live coverage on NASA TV and via the Internet begins at 8:30 p.m. PST 
(11:30 p.m. EST) from mission control at NASA's Jet Propulsion 
Laboratory in Pasadena, Calif. Coverage also will include segments from 
the Lockheed Martin Space System's mission support area in Denver. A 
post-flyby news conference is planned on Feb. 15 at 10 a.m. PST (1 p.m. 
EST).

For NASA TV streaming video, scheduling and downlink information, visit:
http://www.nasa.gov/ntv .

The live coverage and news conference will also be carried on one of 
JPL's Ustream channels. During events, viewers can take part in a 
real-time chat and submit questions to the Stardust-NExT team at:
http://www.ustream.tv/user/NASAJPL2 .

During its 12 years in space, Stardust became the first spacecraft to 
collect samples of a comet (Wild 2 in 2004), which were delivered to 
Earth in 2006 for study. The Stardust-NExT 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.

A press kit and other detailed information about Stardust-NExT is online 
at: http://stardustnext.jpl.nasa.gov .
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Regards,
Eric