LESS than an hour after Genesis had crashed into the Utah desert a television commentator had already raised the question: could this craft be bringing back some kind of 鈥淎ndromeda strain鈥�, an unknown, dangerous organism from deep space.
The consensus among NASA scientists, however, is that the risk from contamination is low. The region of space visited by Genesis, near the Earth, contains the kind of cosmic dust that has been raining down on Earth every day for billions of years. Studies have shown that any organisms in the dust would survive the gentle entry into the atmosphere, so whatever is lurking out there, we鈥檝e been getting it all along.
One lesson to learn from the failure is to prepare for a hard landing, says John Rummel, NASA鈥檚 planetary protection officer, who is responsible for preventing contamination. Since no parachute system could be made foolproof, a crash-landing must be planned for from the start. Tests by NASA have shown that a specifically designed craft should have no problem surviving a hard landing, he says.
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These ideas will come too late for the two missions now on course to bring back extraterrestrial material from elsewhere in the solar system. One of them, the Japanese craft Hayabusa (formerly known as Muses-C) will arrive at asteroid 1998 SF36 next year, grab a gram of space rock and return in June 2007 to a landing site in the Woomera protected area in Australia. NASA and others have looked at the potential risks and concluded that even though a parachute failure and crash-landing could cause the spacecraft鈥檚 container to crack, the risks of contamination are 鈥渆ssentially nil鈥�, Rummel says.
In January 2006, NASA鈥檚 Stardust mission will bring a potentially more worrying cargo back to Earth 鈥� a sample of Comet Wild 2. This will be the first extraterrestrial material collected for return to Earth since the Apollo 17 mission to the moon in 1972.
Comets contain molecules thought to be the precursors of life. And Stardust shares the descent system that went so dramatically wrong for Genesis. But while Rummel believes the risks to Earth are minimal, the Stardust team must await the analysis of the Genesis accident to see what they can do to avoid their craft suffering the same fate.