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.U39 Jeffrey Campbell Barnett Black Snake Leather Stud Flat Loafers Women Sz 10 M , Sequins, Beads TWO pairs one Pink, one Lilac slippers/shoes BP, size 10 Bling!$98 Blake Brody Womens Chelsea Yoga Ballerina Mary Jane Shoe,Blue/Charcoal,US 6Clarks Bendables Women's Brown Leather Slip On Loafers Clogs Shoes Size 7.5M , Xhilaration Women’s Ballet Casual flats Size 9Womans Clarks Classic Loafer, Sz 7.5 Medium Navy, No 26084964 Marine Cuir Pelle , 6.5 M | SAS Penny J Women Black Leather Snakeskin Slip-On Flat Loafer Moc Shoe , STEVEN by Steve Madden Womens Nc-Beck Almond Toe Slide Blush Multi Size 9.5 XO , Demonia Creeper-602 Platform Shoes - size 4m/6w - black leather - rockabilly , Jambu Women's Dory Ballet Flat, Light Grey, Size 6.5women's shoes SERGIO CIMADAMORE 10 () slip on black leather BX406 , Zara Red Women’s Faux Patent Leather Loafers Size 7.5Merrell Black leather Ballet Flats Women's US size 10 ~ Euro 41 Shoes Slip On , Lucky Brand Women`s Size 7 NEW Great Look! Trainer. , 2017 NEW Women's Ladies canvas Sport Running Sneakers Trainers Shoes HOT SELL ! , FitFlop Women's F-Sporty Flower Ballerina Ballet Flat, Silver, 8.5 M USTory Burch Reva Bow Snakeskin Patent Leather CapToe Silver Ballet Flats Sz 7Women's Nike Flex Experience RN White/Pink/Blue Running Shoes 525754-013 Sz 11 , NIKE Woman's AIR VISI PRO 2 Sneaker's Size: 7.5 M , VINCE Women Shose Sneakers COPLEY, GRAPHITE FB Brandnew with box , Converse F HiTop Chuck Taylor All Star Zebra Women Shoes 7 , Skechers Active Classics Women's Vintage Athletic Shoes Size 8 MNEW SKECHERS DOUBLE UP - SHORTY (BLACK)Women's POINTER WOMENS COREY CRIMSON Outfall Athletic Shoes , REEBOK BS9944 FREESTYLE HI Wmn's (M) Silver/Steel Synthetic/Leather Hi-Top Shoes , Hoka One One Bondi 4 Women's Grey/Turquoise Running Shoes 10.5M , New Balance Womens - Blue Running Shoes Size 7.5 (361875) , New Skechers 14958 BBK You Rise Black Women's Casual Shoes 6.5 USWomens Sperry Top-Sider Seacoast Water Jaws Shoes Size 7 Blue White STS97113 , ASICS GEL ZARACA 4 GS C570N women's shoes pink sports sneakers fluo running ,
"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."