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.Womens Size 8.5M Delia's Brown Loafers/Flatslalite-2-b New Fashion Nubuck Slip On Casual Women Flats Wonem Shoes Black 5.5 , Born Concepts Women's Maroon Leather Slip On Round Toe Ballet Flats US Size 8 MMunro American Women's Shoes, Size 5.5, Brown Grey. Nice!Women's MONTANA Leather Clogs 6M Black Slip On Studded Shoes Buckle Mules , Pink Cute Pig Lightweight Slip-on Canvas Women's Casual Flats Shoes , FitFlop Hisbiscus Sling Women Sz 7 M Strappy Slingback Sandals Red Pink 284-258Cole Haan Air 7.5 Monica Cream Ballet Flat Bow Detail Comfort Work Career CasualB35 Opal Slip On Loafer Flats, Denim, 5.5 US DisplaySoft Spots Brown Leather Loafers Flats Slip On Women's Comfort Shoes 8.5M $110Born Laina Women's Nude Waxed Suede Comfort Slingbacks Shoes, size 9 NEWSkechers Women’s Sz 8.5 Leather Shape Ups PreownedEasy Spirit White Leather Walking Shoes MACH I Sneakers - Size 9N NarrowLadies NERO GIARDINI Sport Sneakers. Sz 7 , Propet Tour Walker Sneaker - Women's Size 8W White , CONVERSE Neon yellow green volt black LOW TOPS 153919F Womens sneakers chuck NEWDKNY BOBBI leather Sneakers Shoes Women's 9 Black Gold Donna Karan NYConverse Allstar Athletic Shoes Women's Size 9 Pre-ownedREEBOK WHITE LEATHER SNEAKERS SHOES WOMENS 9 FREE SHIPAsics T272N Gel Neo 33 Womens Running Training Shoes Size 8.5 Green D5Women's South African Ladies Running Shoes Fashionable And Attractive Packages Athletic ShoesREEBOK sz 6 WOMENS SNEAKERS - MULTI COLOR - NWOB SHO-8 , Ecco Biom FL GTX Trail Running Shoes Hiking Size US 5 / 5.5 Orig. $190 , Sneakers and Athletic Free People Naples Slip-On Sneaker White , Puma Vikky Mid Corduroy Olive Night free shipping , Skechers D'Lite Ultra Black Black For Women's With Memory Foam New In Box , New Rockport WALK360 Washable Slip-On Women Shoes Size 9 , New Balance Womens 696 ReEngineered Blue Sneakers Shoes 5 Medium (B,M) BHFO 3347Camel Crown Running Shoes Women Athletic Shoe Non Slip Sneakers Youth Fashion BM , RYKA Ryka Womens Jenny Fashion Sneaker- Pick SZ/Color. ,
"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."