Things are happening on Mars January 15, 2009Posted by Sarah in science.
Tags: astronomy, life, mars, methane, nasa, space
Earlier today, The Sun reported that evidence of little green men on the Red Planet had finally been spotted. Not so, said the scientists in a briefing this evening – or at least not necessarily, not definitively so. But it looks like we may have come just one small step closer to discovering if life exists on the Red Planet. For the first time, firm evidence has been found that active processes are taking place on Mars, possibly biological in nature, and this is an exciting find.
Using the Infrared Telescope Facility on Mauna Kea, Hawaii, a team of scientists led by Michael Mumma of NASA’s Goddard Space Flight Center have spotted methane being released into the Martian atmosphere. Remarkably the methane detection was confined to a few “hotspots” without being dissipated uniformly into the atmopshere by the wind, like we see here on Earth. This means that for some reason, the methane has a very short lifetime in the atmosphere, and is possibly being actively destroyed. The observed hotspots were seen in early 2003, during the Northern hemisphere sason on Mars; the following year they had disappeared.
Methane can be produced below the Martian surface in geochemical interactions between rocks and water in a process called serpenization serpentinisation. Sublimation of material off the surface with the changing seasons could then open vents at particular times of the year, from which gas is released. But serpenization serpentinisation as we know it on Earth is typically accompanied by more signs of geological activity, such as uplifting and fracturing, and no evidence for such phenomena have been found on Mars. No other gases commonly associated with geological activity, such as sulfur dioxide, have been detected. A more catastrophic origin of the methane, such as a comet slamming into to the Martian surface in the last few hundred years, seem unlikely to have gone unnoticed by stargazers here on Earth.
Methane is also well known to be produced in biological processes here on Earth, and the existence of microbial life below the Martian surface cannot be ruled out. The microbes could live deep down scarp walls, where the gas can only be released periodically when the seasons change, or in salty aquifers isolated from the surface by a layer of permafrost.
Finding the silver bullet, however tantalising, will not be easy. Further spectroscopic studies from the ground could show evidence of more biomarkers, that are conclusively known to be produced only in biological processes. But even if such markers are spotted in Mars’ atmosphere, it can take years to rule out all other possible mechanisms to put it there. The only other way to be sure is to physically find life and try growing it. Martian microbes may resides several metres, or even kilometers below the Martian surface – far to deep for any of the rovers or the Mars Science Laboratory to dig.
The NASA Mars team may however reassess the potential landing sites for MSL in view of these results.
The team have vast amounts of data from 2003 to 2008 to plow through yet, and they were unable to comment on preliminary findings from other seasons. In their further work, they will study the isotopic abundance ratios of water, correlation of the methane detection with other volatiles found in the atmosphere. Each result has to be diligently checked and rechecked for accurate calibration and systematics in the instrument. An observing run on the state of the art infrared spectrograph CRIRES on the Very Large Telescope in Chile is planned for August 2009. This is a pretty great instrument that uses adaptive optics to remove effects of atmopsheric turbulence in the images, greatly increasing its resolution and sensitivity. So we can expect much more fascinating science from this team, perhaps even a clue to yet another holy grail of astronomy: life outside Earth.
The methane findings will be reported by Mumma and colleagues in Science. Image credit: NASA