The latest revelations about 鈥渁lien life鈥� suggest the agency should focus more astrobiology and less on publicity
鈥淚T鈥橲 life, but not as we know it,鈥� trumpeted one headline. 鈥淎lien life may have been discovered 鈥� right here on Earth,鈥� gasped another. Even The New York Times declared 鈥淢icrobe Finds Arsenic Tasty; Redefines Life鈥�.
The breathless write-ups followed NASA鈥檚 teasing announcement of a news conference 鈥渢hat will impact the search for evidence of extraterrestrial life鈥�. And although the discovery of alien life, if it ever happens, would be one of the biggest stories imaginable, this was light years from that.
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What we got was a paper published in Science purporting to describe a bacterium that has replaced phosphorus throughout its biomolecular machinery, including DNA, with arsenic. If true, it would be the first time a life form has been discovered that can operate without phosphorus 鈥� thought to be one of the elements essential to life 鈥� and the first time that an alternate working form of DNA has been seen in an organism. Not ET, then, but even the existence of an arsenic-based bacterium would extend the known boundaries of life.
Yet it is far from clear that a 鈥渟hadow biosphere鈥� has been found. The paper has already been attacked by scientists who say the evidence that arsenic is actually incorporated into the bacterial DNA is weak (see 鈥淧oison eaters: alternative life forms鈥�).
聯It鈥檚 far from clear that a 鈥榮hadow biosphere鈥� has been found. The paper has already been attacked聰
NASA has been in these waters before. In 1996 in Science the space agency described how a Martian meteorite found in Antarctica might contain traces of fossilised microbial life. Bill Clinton, the US president at the time, announced the discovery on television. Controversy over the evidence flared up immediately and it continues today.
The creation of this new frenzy is surprising, considering that the search for extant life on Mars in particular seems to be . Why does it allow 鈥� encourage, even 鈥� such hype? Perhaps it thinks that all publicity is good publicity, but one day the appetite for sensationalist alien life stories may be sated.
As Carl Sagan once remarked, extraordinary claims require extraordinary evidence. NASA might soon be wishing it had heeded this advice.