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.Footzyrolls The Rollable Shoe Wondrous White 3 Steps To Street Walkable Flats , New Women's Size 6.5 Sperry Duckling Navy Blue Top-Sider Waterproof Rubber BootLucky Brand Womens Size 7 Ballerina Flats Black (A-07)Skechers Womens Disco Bunny Clog Mule Heel Fuzzy Fur Slip On Shoe Suede Brown 96.5 M | Clarks Evianna Mix Women Black Leather Slip On Flat Clog Loafer MocCole Haan N Air Loafer Womens Size 6 B Leather Moccasin Animal Print Slip OnCole Haan-- Air --Mules Red Nubuck Flats-- Comfort Shoes--- MSRP $135---6BZara Basic Women’s Gold Drees Shoes Size 37 USA 6 1/2 , Women's Sperry Top-Sider Billfish Tan Leather Boat Shoes US 8 MTanara Athletic Women`s Shoes Size 7 Leather Color white Flat shoes EXCELLENTAGL Attilio Giusti Leombruni Black Leather Patent Cap Toe Flats Buckle SZ US 7JOSEF SEIBEL COMFORT SUPPLE LEATHER MULE CLOG SIZE US 11 HOT RARE $129**Tretorn Match HI3 Sneaker - Women's Size 7.5, BlackSaucony Womens Grid Tornado 5 Sz 7.5 Running Shoes G8 , Hi-Tec Women's Hiking Sneakers Boots Shoes Suede Fabric Brown Grey 8.5 , Munro 'Berkley' Shoe Red Leather Women's size 9 M New in BoxWomen's New Balance Running Vazee Coast Black/White WCOASBK Brand New In Box , Brooks Ghost 10 Womens Sz 9.5 Primer Grey Running Training Athletic Shoe ZU-828Kenneth Cole REACTION Salt-N-Pep Fashion Sneakers 079, Black Haircalf, 9.5 US /Skechers Double up Ditsy Darling Womens Slip On Sneakers , Skechers Performance Women's You Define Wide Sneaker - Choose SZ/Color , Women's Women's Loudmouth Loafers Reputation First Flats , STEVEN by Steve Madden Hilda Slip On Fashion Sneakers 608, Black, 7 USVANS Sk8 Hi Moc (Tortoise) Black/Blanc Leather High Top WOMEN'S Size 8North Face Ultra Equity Hiking/Trail Running W8New Balance Fresh Foam Zante Womens Running Shoes Coral Pink Sz US 10 , Saucony Womens Peregrine 7 Mesh Athletic Support Terrain Running Shoes Size 10.5 , Skechers Womens Training Shoes 9.5 A05Sanuk Women's Vee K Shawn High Top , NIKE DUAL FUSION 8.5 WOMENS / 7 YOUTH GIRLS SHOES SNEAKERS BLACK RED BASKETBALL ,
"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."