Curiosity's search for life has turned up some disappointing news. According to test results published today in Science, the search for methane-producing microbes on Mars has turned up empty.
The odds for life on Mars are looking slim
The story starts with a 2003 report that detected plumes of methane on Mars, giving many hope of finding microbial life as a result. Unfortunately, the new study reports that after years of searching, Curiosity's spectrometer has yet to turn up a measurable quantity of methane in the atmosphere. Today's report doesn't mean there's no methane at all on Mars, but without enough to measure, the odds of finding methane-producing life on Mars are looking slim. There's also the chance that Mars is hosting a form of microbe that doesn't produce methane, which are extremely rare but have been discovered on Earth before.
Update: As the Curiosity team stated in the report, "there are micro-organisms that don't produce methane, so we're not totally giving up on the possibility of Martians just yet." They've since reiterated this point on Twitter.
Lack of methane doesn't mean Mars never supported life. Plenty of Earth organisms don't produce the gas.— Curiosity Rover (@MarsCuriosity) September 19, 2013