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.Clarks England Cicely Brown 8M Mules Clogs Slip-on Side Buckle , Sesto Meucci Black Patent Leather w/ White Flower Ballet Flats Shoes 7.5 M AX , Merrell Jungle Moc Sport MJ Black Suede Mary Jane Sneaker Loafer Shoe Womens 6 WMERRELL Womens Sz 7 Brown Leather Air Cushion Slip On Walking Loafer Moccasin-37Cole Haan Women's Slides Moc Toe Mules Red Leather Casual Shoes 7.5Aerosoles Women's Best Wishes Faux Leather Low Top Loafer , MERRELL Circuit MJ Womans Sz 7 Brown Tan Suede Slip On Shoes Mary Janes Flats , Circus by Sam Edelman Collins Watermelon White Leather Sneaker Shoes Women's 8.5Skechers Women's PLUSH LITE - WINTER SKIES Walking ShoesEastland 1955 moccasins shoes 8.5 M leather new blue gum soleLita oxford wingtip like ne only worn inside, see photos , Mismate Womens Nike Free Rn Run 2017 880840-003 Black Size 8/7Nine West New Starship Multi-Color Womens Shoes Size 7.5 M Flats MSRP $69 , Steve Madden Pazer Women's Metallic Gray Flats 9.5 M , Blowfish Women’s Shoes Malibu Cayo Pastel Grey Size: US 7 MJambu leather tennis shoes size 7S.A.S Tripad Comfort Women's Slip On Loafers Size 6.5 M Shoes Blueish Gray R7S7 , Sam Edelman Womens Baylee Soft Silver/Fog Grey Fashion Sneaker Size 8 (29872) , New! Women's Skechers 12404 Empire - Heart to Heart Walking Shoe - Grey/Mint O39New Balance Womens WX77VC2 Navy Trainers Sneakers 5 Wide (C,D,W) BHFO 8607Women's Replica Air Transparent High Top Athletic Shoes Orange & Black Size 13 , New Balance 77V2 Women's Cross-Trainer Running Shoes Sneakers8.5 - Nike Flyknit Air Max Womens Running Shoes 620659-001 Sneakers 0905JGWomen's Nike Air SB Dunks Complete In Specifications Athletic ShoesConverse Star Player Evolution Black White Womens TrainersBrooks Ariel '16 Running Shoes, Women's Size 9.5D, Teal/Black , Brooks Ladies 8 Medium Addiction Walker Walking Work Black Leather SneakersSkechers Women's Black Shape Up Sneakers Size 8 , Women’s Nike Free Run 3 Sneakers In Gray, Size US 10 , NWOB WOMEN'S CONVERSE CHUCK TAYLOR ALL STAR OX PATENT LEATHER EGRET/WHITE SIZE 7
"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."