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.Dr Scholls size 7 W black tie men's work shoes , Natural Sole Seaside Casual Shoe, Red Pepper, Women's US Size 6.5Crocs Womens Size 9 Brown Mary Jane Ballet Flats Rubber Slip On ShoesBorn Women's Black Leather Mary Jane Shoes Buckle Size 8 / 39 M BOC FALL , E-G1 women lady basic ballet flats slip on shoes Size 5.5~9Bellini Womens Formosa Pointed Toe MulesCole Haan Womens Mules Brown Leather Vintage 2002 Good Condition $125 MSRPTahari Gibson Women's Ballet Ballerina Bow Flats Slip On ShoesTommy Hilfiger Women's Denim Espadrille US 7.5 () , PARE GABIA Shoes 180919 Purple 36Cole Haan ZeroGrand Mesh Slip-On Sneaker Shoe - Women's 9 - SALE BENEFITS RESCUE , Zalo Black Velvet Kitten & Puppy CHRISTMAS Shoes Size 7 M BEAUTIFUL Spain.!Danskin Now Womens White I-Net Technology Shape Up Walking Shoes size 6.5NIKE WOMENS YOUTHS FLIP FLOPS POOL SLIDERS SLIPPERSWomen's SAS Brown Suede TriPad Comfort Casual Comfy Oxford Sz. 11.5 EXCELLENT , Ariat Light Brown Woven Leather Clogs Women's Size 7.5 M Style GUC Nice!Woman Canvas Shoes Casual Sneakers Sports Shoes Floral Print Slip-on Walking HOT , Easy Spirit Sherwin sneakers shoes new sz 6 1/2 MVANS Kaylin Mid Women's Leather Skate Shoes Size 6 VN-01NL4BH FREE Shipping! , Women's Skechers Size 8 Sport White & Silver Athletic/Walking Shoes Memory FoamWomens City Snappers Platform Camouflage Sneakers Sz 10New Balance Women's 620 Shoes Tan 12 B , Brooks Adrenaline GTS 13 Running Shoes Women’s Size 11 (2A) US Excellent PlusKarhu Fulcrum Fast 7 MRE Shoes CRUSHED VIOLET RASPBERRY women's Size 9.5 EUCNew with Box Saucony Women's ProGrid Lancer 2 Running Shoe Size 6 Blue w/ Coral , New! Women's Nike 831509-400 Free RN 2017 Shoe - Aqua/Fuschia O64 , Nike Air Force 1 HI Premium Womens 654440-009 Black Sail Gum Shoes Size 9 , Women Nike air Max Athletic Shoes Size 7.5 black color 621078- 007Vans Off the Wall Womens Surf Shoes Palisades Vulc Distressed Teal Womens 5 , Propet RidgeWalker Low - Women's Orthopedic Hiking Shoe - All Colors - All Sizes ,
"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."