Curiosity: stronger support for life on Mars Dec 11 2014
Whilst roving about Mars, Curiosity has slowly but surely racked up evidence for a past Mars that was warm, wet, and possibly habitable.
John P. Grotzinger of Caltech, the project scientist for the mission, reported at a news conference on Monday that the rover's yearlong trek to Mount Sharp provided strong new evidence that Gale Crater had large lakes, rivers and deltas, on and off, for millions to tens of millions of years. The geology shows that even when the surface water dried up, plenty of water would have remained underground, he said.
Moreover, the team concluded, numerous deltalike and lakelike formations detected by orbiting satellites are almost certainly the dried remains of substantial ancient lakes and deltas. None of this proves that life existed on the planet, but the case for an early Mars that was ripe and ready for life has grown stronger.
"As a science team, Mars is looking very attractive to us as a habitable planet," Dr. Grotzinger said in an interview. "Not just sections of Gale Crater and not just a handful of locations, but at different times around the globe."
See also the interactive 28 Months on Mars.
Update: And right on cue, Curiosity has recorded a two-month-long methane burst on Mars. One explanation for the methane is that it's a waste product of living organisms.
The presence of methane is significant because the gas cannot exist for long. Calculations indicate that sunlight and chemical reactions in the Martian atmosphere would break up the molecules within a few hundred years, so any methane there now must have been created recently.
It could have been created by a geological process known as serpentinization, which requires both heat and liquid water. Or it could be a product of life in the form of microbes known as methanogens, which release methane as a waste product.
Even if the explanation for the methane turns out to be geological, the hydrothermal systems would still be prime locations to search for signs of life.
Update: And now Curiosity has found "biologically useful nitrogen" on Mars.
There is no evidence to suggest that the fixed nitrogen molecules found by the team were created by life. The surface of Mars is inhospitable for known forms of life. Instead, the team thinks the nitrates are ancient, and likely came from non-biological processes like meteorite impacts and lightning in Mars' distant past.
Features resembling dry riverbeds and the discovery of minerals that form only in the presence of liquid water suggest that Mars was more hospitable in the remote past. The Curiosity team has found evidence that other ingredients needed for life, such as liquid water and organic matter, were present on Mars at the Curiosity site in Gale Crater billions of years ago.
"Finding a biochemically accessible form of nitrogen is more support for the ancient Martian environment at Gale Crater being habitable," said Jennifer Stern of NASA's Goddard Space Flight Center in Greenbelt, Maryland.