The Red Planet may be capable of supporting microbial life some scientists say. At "The Present-Day Habitability of Mars" conference held at the University of California Los Angeles this month several researchers stressed that microbes can eke out a living in extremely cold and dry environments. They explained, “Not all parts of the red planet's surface may be arid currently.” Evidence is building that liquid water might flow seasonally at some Martian sites, potentially providing a haven for life as we know it. "We certainly can't rule out the possibility that it's habitable today," said Alfred McEwen of the University of Arizona, principal investigator for ‘HiRise’ NASA's Mars Reconnaissance Orbiter spacecraft.
McEwen discussed some intriguing observations by HiRise, which suggest that briny water may flow down steep Martian slopes during the local spring and summer and sixteen such sites have been identified to date. "Briny water on Mars may or may not be habitable to microbes, either from Earth or from Mars," McEwen said. Martian life may be able to survive even in places where water doesn't seep and flow. For example, microbes here on Earth make a living in the Atacama and the dry valleys of Antarctica, both of which are extremely cold and arid. Here organisms dwell within rocks, just deep enough to be shielded from the worst of the UV but close enough to the surface to receive the benefits of photosynthesis. Something similar might be happening on Mars today, if life ever evolved there.
McKay offered some advice to NASA's Mars rover Curiosity, which landed in August to determine whether Mars could ever have supported microbial life. While the Curiosity rover and its newly remembered sibling Opportunity scan the surface of Mars for life and other oddities, it’s up to scientists back here on Earth to determine if life is even possible in the Martian climate. To recreate the harsh conditions of the surface of Mars, Alexander Pavlov and his team from the Goddard Spaceflight Center used a sample of salty dirt similar to what has already been detected on Mars and placed it under a bell jar with an atmosphere of carbon dioxide. The scientists cooled this environment with liquid nitrogen and then added water and a specimen of E. coli before gradually lowering the pressure.
The simulated environment would have to further decrease its pressure to make a definitive statement about how well E. coli and other microbes could survive on Mars, but it’s still promising, and the severely decreased pressure relative to Earth shows that life could be possible on planets with thinner atmospheres than our own.
Photo by NASA.
