PARIS - Salty water just below the surface of Mars could hold enough oxygen to support the kind of microbial life that emerged and flourished on Earth billions of years ago, researchers reported Monday (Oct 22).
In some locations, the amount of oxygen available could even keep alive a primitive, multicellular animal such as a sponge, they reported in the journal Nature Geosciences.
"We discovered that brines" - water with high concentrations of salt - "on Mars can contain enough oxygen for microbes to breathe," said lead author Vlada Stamenkovic, a theoretical physicist at the Jet Propulsion Laboratory in California.
"This fully revolutionises our understanding of the potential for life on Mars, today and in the past," he told AFP.
Up to now, it had been assumed that the trace amounts of oxygen on Mars were insufficient to sustain even microbial life.
"We never thought that oxygen could play a role for life on Mars due to its rarity in the atmosphere, about 0.14 per cent," Stamenkovic said.
By comparison, the life-giving gas makes up 21 per cent of the air we breathe.
On Earth, aerobic - that is, oxygen breathing - life forms evolved together with photosynthesis, which converts CO2 into O2. The gas played a critical role in the emergence of complex life, notable after the so-called Great Oxygenation Event some 2.35 billion years ago.
But our planet also harbours microbes - at the bottom of the ocean, in boiling hot springs - that subsist in environments deprived of oxygen.
"That's why - whenever we thought of life on Mars - we studied the potential for anaerobic life," Stamenkovic.
LIFE ON MARS?
The new study began with the discovery by Nasa's Curiosity Mars rover of manganese oxides, which are chemical compounds that can only be produced with a lot of oxygen.
Curiosity, along with Mars orbiters, also established the presence of brine deposits, with notable variations in the elements they contained.
A high salt content allows for water to remain liquid - a necessary condition for oxygen to be dissolved - at much lower temperatures, making brines a happy place for microbes.
Depending on the region, season and time of day, temperatures on the Red Planet can vary between minus 195 and 20 deg C.
The researchers devised a first model to describe how oxygen dissolves in salty water at temperatures below freezing.
A second model estimated climate changes on Mars over the last 20 million years, and over the next 10 million years.
Taken together, the calculations showed which regions on the Red Planet are most likely to produce brine-based oxygen, data that could help determine the placement of future probes.
"Oxygen concentrations (on Mars) are orders of magnitude" - several hundred times - "greater than needed by aerobic, or oxygen-breathing - microbes," the study concluded.SPERRY Top-Sider Cheetah Print Leather Tassels Ballet Flats Shoes WOMENS 6 MWomen's ❤️ Børn ❤️ Red Clogs Plaid Born Mules Slip On Casual Shoes Sz 10 / 42Merrell Ortholite Women’s Slip On Moc Size 8.5 BrownFree People Womens Mainland Slide Sandals Shoes Black Size 38 NewARRAY Womens Freedom Leather Square Toe Loafers, Beige, Size 10.5 ui3t , Vince Camuto “Salina” Perforated Oxford Size 8.5 , Kenneth Cole New York Wallice Slip-On Flat Mules, Mutli, 9 US / 40 EU , EARTHIES ESSEN LEATHER BALLET FLAT SHOES NEW SIZE 7.5 , Indigo Rd. Women's Cyndy Sneaker, Red, 9 M USPRE Speedo Women's Port Lightweight Breathable Water Shoe pk size color , Vasque Women's Talus Trek Low UltraDry Hiking Shoe Black Olive/Damson Size 7M , Womens Saucony Cohesion 10 Gray Running Shoes Size 9M (C8) , Womens Girls Puma Shoes Size 6 , Saucony Triumph 11 Running Shoes Power Grid Pink Gray Women’s Size 6Jessica Simpson Womens Raquelle Flat Sandal- Pick SZ/Color.Women's Nike Air Force 1 Mid Clearance Price Athletic ShoesWomen's NEW STEVE MADDEN WOMENS GRADUAL Economy Athletic ShoesPUMA Aurora Borealis Pink Violet Gold Shimmer Hightop Gold Logo 8 Unreal Color , On Cloud Athletic Shoes - Women's Size 9, Black/GreyGUESS Womens VALLERI Fabric Low Top Fashion, Silver multi, Size 7.0 jNj5 , $130 North Face Women's Ultra MT Size 7 Red/Blue NEWWomens Nike Dunk High Tweed Baroque Brown University Blue Obsidian Size 6 SB , Merrell Yokota Womens Waterproof Hiking Trail Running Shoes Size 10 Brown BlueSkechers Womens Shape-Ups Pink Grey Leather Size 9 US SN 11806 Free Shipping , Vans VN-OX-JOF4K low canvas blue Red floral US 9 Medium womenSkechers Navy Coral Zen Bungee Slip on Walking Sneakers Shoe 10 W SALE , Womens Gray Nike Free Xilla Run 5.0 size 9 , Skechers BOBS from Women's Burlap Wedge Espadrille Fashion Black Size 5.0 , New Womens Size 8 Nike Air Max Thea Ultra FK Geranium/ Geranium Blue Tint , Nike Air Max Airmax 90 Ultra Essential Running Shoes, Black/Dark Grey/Pure 8 ,
"Our results do not imply that there is life on Mars," Stamenkovic cautioned. "But they show that the Martian habitability is affected by the potential of dissolved oxygen."