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.Bobs for Dogs by skechers 6.5 black kitten cat comfort loafers Flats Shoes , CROCS Woman's Size 11 purple slip on shoes , WOMENS LADIES CASUAL WORK PUMP SHOES SMART BUCKLE STRAP DETAILS SHOES 3-8 , Cole Haan NikeAir Gold Metallic Ballet Flats Womens 8.5B , SAS Size 9 Slim Tripad Comfort Foot Bed Leather Shoes Slip On Womens 9 S (AAA) , Banana Republic Sz 7 Brown Leather Loafer Driving Flat Moccasin Shoes For WomenMerrell Women’s Brown Slip-On Performance Grip Clog Shoes Sz9 $35 , Kenneth Cole REACTION Women's Pro-Time Elastic Ankle Strap, Back, Navy, Size 9.0 , Cole Haan black clog nubuck and mesh upper slip on / zip up size 8.5 B nike airNew Jambu Blush - Barefoot red women's shoes size 7$120 Dolce Vita Black Colette Two-piece Leather Woven Espadrilles Flats Size 8.5 , Adidas 3-D Cushion TORSION SYSTEM Athletic Womens Shoes size 10 Black/White , Eastland Womens gia Leather Almond Toe Ballet Flats Navy Size 7.5 iRfYEasy Street Womens Charlize Closed Toe Ballet Flats Black Size 9.0 , ??? Mens Leather Slippers ? BLACK Shoes Size 7 8 9 10 11 12 13 Flip-Flop?New Balance Women’s 792 Blue And Purple Running Shoes Size 9Womens Hollow Out Slip On Hidden Wedge loafers Casual Atheltic Sneakers shoes USWomen's SKECHERS *NEW* 9.5 SNEAKERS Ample Supply And Prompt Delivery Athletic ShoesWomen's Propet Women's Sonia Sale Price Athletic Shoes , New Balance 928V2 White Leather Wide Toe Strap Shoes Sneaker Rollbar Walking 6Nike Womens Air Max Thea Run Running Black Summit White 599409-020 8.5 9 10.5 12New Balance Women's 247 Winter Shimmer Shoes Purple with PinkNew Balance Fresh Foam Zante 3 Running Shoes, Women's - Size 8.5 B, Grey/PinkASICS Jolt Black - Womens - Size 8.5 B , Sperry Womens Crest Ebb Sandwash Sneaker ROSE STS80096 SIZE 5 MSkechers Women's You Zen Sneaker - Choose SZ/Color , Merrell Womens J18514 Brindle Hiking Shoes Size 9 (34027) , TEVA Womens Original Flatform Universal Sandal White / Yellow Platform US 10 NEW , Womens Asics Gel Flux 2 Running Gray Grey Pink Size 9SHINY GOLD..PLATFORM..SNEAKERS..w STUDS, SPIKES..STEVE MADDEN..Sz 9 ,
"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."