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Moon Impact: NASA Plays Down Lack of Fireworks (转载)
[版面:南京航空航天大学][首篇作者:NUAA] , 2009年11月02日14:07:34 ,209次阅读,0次回复
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发信人: NUAA (呦呦鹿鸣), 信区: NUAA
标  题: Moon Impact: NASA Plays Down Lack of Fireworks
发信站: BBS 未名空间站 (Mon Nov  2 14:07:34 2009, 美东)

【 以下文字转载自 Aviation 讨论区 】
发信人: ZZGR (闲逛), 信区: Aviation
标  题: Moon Impact: NASA Plays Down Lack of Fireworks
发信站: BBS 未名空间站 (Mon Oct 12 13:06:11 2009, 美东)

By Richard A. Kerr
ScienceNOW Daily News
9 October 2009
NASA officials and scientists spent the better part of an hour in this
morning's press conference patting themselves on the back. The LCROSS
mission in search of lunar water was a great success, they said, all the
while ignoring a very large elephant in the room: No one among the millions
watching as a 2-ton hunk of metal slammed into the moon could see the much-
ballyhooed spray of dust and debris that they had been told to look for.

Even LCROSS scientists have seen nothing of a debris plume. "I'm not
necessarily surprised," said LCROSS principal investigator Anthony Colaprete
of NASA's Ames Research Center in Mountain View, California. In exploration
, "you just never know how these things are going to go. We just have to go
back with a finer-tooth comb." Colaprete's dogged optimism is grounded in
enticing spectroscopic changes detected around the impact site. Determining
whether it was water will take weeks or months of data combing.

Actually, Colaprete had warned his colleagues, at least, about the
possibility of a no-show debris plume. "It's a very unproven and highly
unpredictable science, impact cratering," he told an audience at the Lunar
and Planetary Science Conference last March. Impact modelers working for the
team had struggled to simulate the impact of a cylindrical--not a simpler
spherical--object, and one that was hollow, not solid, like the LCROSS
impactor. Plus, it smashed into a surface of unknown shape and composition.
LCROSS was "the most challenging impact modeling I've ever done," said Erik
Asphaug of the University of California, Santa Cruz. There were just too
many unknowns for him to be entirely comfortable with his results; impact on
the odd unseen boulder, for example, could have sent most of the debris
into the crater wall instead of into the sky.

LCROSS scientists may yet extract a debris plume from the data, but "the
spectra is where the information is" about any water, Colaprete said,
referring to spectral colors in the visible, infrared, and even ultraviolet
returned by the trailing LCROSS spacecraft and by the Lunar Reconnaissance
Orbiter. Some of these showed intriguing blips from the impact flash and the
still-warm crater. There were also spectral changes above the impact site
between pre- and postimpact. "What do these little blips mean? I don't know,
" Colaprete said. "I'm just glad they're there. We're going to work on this
feverishly." Even so, no public word about water will be forthcoming before
the December meeting of the American Geophysical Union, he said.

Start rooting now for the blips.
--

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