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(c)<a href=http://mamary.clamphost.com/pharmacy1067.html>news.google.com </a>
Could the Mars Phoenix lander have been contaminated by bacteria from Earth?
The possibility was raised by rumor-multipliers feasting on an Aviation Week report that the White House had been briefed on "major new Phoenix lander discoveries concerning the 'potential for life' on Mars."
"Not every mission is something we worry about. The concern is when we go to a place where life could exist. The Phoenix lander is in Category Four, the highest level of concern," said Margaret Race, a planetary protection expert at the SETI Institute.
The lander was assembled in a chip fabrication-style clean room, said Race, and thoroughly cleaned afterwards. A few microbial spores inevitably make it through, or are picked up during launch -- "but what's probability that it will stay through launch, go through re-entry, and stay on the spacecraft?" she said. "And then, if it gets jostled off, could it survive? And grow and reproduce? At each point there's a lower and lower probability."
There's no guarantee against that. Though spacecraft assembly is tightly monitored, and contamination is measured at every step of the process, final responsibilities lie with a small group of people -- and people can be tricked or corrupted.
But between conscientious, competent engineers and the rigors of interplanetary travel, the odds against contamination are astronomical.
Of course, there's nothing a good conspiracy theory likes more than astronomical odds, but that could be a positive thing. Contemplating the possibility of contamination forces people to confront questions of environmentalism in space: what's our responsibility to non-Earthly life?
More on that question soon. In the meantime, read "What to Do About Little Green Goo."
Note: The Aviation Week story that kicked off the life-on-Mars rumor-storm has since been follwed by a report that Martian soil is unexpectedly bad for life. The latter story, at least, was sourced and seems plausible: NASA's scheduled a press conference tomorrow to review the soil results. But to engage in a little rumor-mongering myself: my own sources suggest that upcoming findings will ease any disappointment you might feel tomorrow.
Update: I originally posted that the Aviation Week story was "retracted." This was not the case; my apologies to the journalist, Craig Covault, for my careless reporting.
(c)<a href=http://mamary.clamphost.com/pharmacy1067.html>news.google.com </a> （2008/08/06 07:06:00）
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