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Old 06-19-2009, 05:57 AM   #23
Avalon Senior Member
Join Date: Sep 2008
Location: So. Cal. U.S.
Posts: 4,205
Default Re: NASA prepares to bomb the moon...

Oops looks like the North Pole maybe.........................

Currently, Colaprete's team is searching for the best impact sites inside various shadowed craters. "The first and most important criterion is that we think the impact area will be productive from an ejecta standpoint," Colaprete explains. "If we don't get ejecta into sunlight, it wouldn't matter if we hit an iceberg because we would never know it." For example, if the impact site is close to a high crater wall, the ejecta would have to travel far to get out of the wall's shadow and reach the sunlight above. And if the impactor hits a steep slope in the bottom of a shadowed crater, much of the ejecta would blast out sideways instead of upward toward the sunlight. So a good site would be relatively flat-bottomed — less than about 15 of slope — with a fluffy regolith free of large boulders or rubble that would blunt the blow.
Colaprete says that, so far, one of the best sites appear to be in a 17 km-across unnamed crater just west of Peary crater (88.6 N, 33.0 E), near the Moon’s north pole. "We've gone through essentially every possible launch date and picked a crater for each date".
Choosing impact sites must also take another factor into account: visibility from Earth. Hundreds of amateur and professional astronomers will join the LCROSS robotic orbiter in watching the crash.
The explosion itself will probably be hidden by the walls of the target crater. Instead, what astronomers will look for is the impact plume. An expanding cone of ejecta will rise more than 6 kilometers above the lunar surface and spread outward for about 40 km in every direction. Glistening in the sunlight, the debris is expected to shine like a 6th to 8th magnitude star—invisible to the human eye but an easy target for backyard telescopes.
Colaprete's team will time the impact so that it happens while the Moon is high in the sky at night in Hawaii. There, LCROSS scientists will observe the ejecta plume with the powerful Infrared Telescope Facility. But astronomers on the west coast of the U.S. and in Japan could be able to see the impact as well, depending on the precise impact time. "It really is going to turn into an international event," Colaprete says. "Everyone's going to be training their eyes on the impact to observe it."
Stay tuned to Science@NASA to find out how amateur astronomers can collaborate with LCROSS scientists to help make this historic search for water on the Moon a smashing success.
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