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.Hot Chocolate Design Mini Chocolaticas Popcorn Girls Mary Jane Flat HCD 25 , A35 Aleaa Ballet Flats 416, Apricot, 7.5 US , Ballet flats sz.7.5M Worthington cranberry suede gold cap toe dress shoesMinnetonka Women's Kilty Unbeaded Moccasin White Smooth 7.5 B(M) US~ EUC , Merrell Women’s Select Fresh Tahoe Soft Blue Nubuck Ballet Flats Size 7LFL by Lust for Life Women's L-Tango Fashion Sneaker, Pastel Multi, 8.5 M USBallerines VIVALDI Paris Cuir Marron T 38 TRES BON ETAT , Nine West Womens Simily Closed Toe Ballet Flats, Black, Size 7.0 , Betty Boop "Movie Star" Women's Canvas Sneakers With Heart Charm NWOB Size 8 , New Born Women's Black Leather Ballet Sz 6.5 MLadies Rieker Brown & Burgandy leather Casual Flat Antistress Shoes 8917406184 , Klogs Valley Womens Leather Clogs Display Model Chocolate Suede 6 M , Women's Merrell "Black' Oiled leather Casual Loafer Sz. 40/9 Excellent!***NEW*** Gola Women`s Astra Tennis Canvas Size 6 U.S.Aerosoles Women's Upper Level Flat, Black Combo, 6 M USReebok Ladies Sneakers Twisted Form Running Shoes Size 8 Black Turquoise GUC , Russian Black Cat Slippers Wool 100% Handmade Valenki Ehma BrandNew El Naturalista N296 Soft Grain Carrot Orange Women's Shoes Size US 6 , Airwalk Canvas High Tops Size 7 , MBT 10 Gray Orange Walking Shoes Women'sBrand New FILA Womens Headway 6 Trail Running Shoes Grey and Pink Size 10 US NIBAsics Gel Quantum 360 Shift (T7E7N-9601) (Medium Grey / White) Womens Running , Skechers Performance Women's Go Walk 2 Backswing Golf ShoeNavy/Pink8.5 M US , WMNS NIKE FREE RN CMTR 2017 PREM AA1622 001 SIZE 5.5~10ZCoil Legend wt Green Trim Womens Sz 10.5 Pain Relief Comfort Walking Sneakers , RICHMOND women shoes sz.6 Europe 36 black canvas leather. S6355 , Asics Gel-Cumulus 16 Turquoise/Sharp Green/Blue T489N Women's Running Shoes 9 , Saucony Redeemer ISO Running Shoes size 6.5 Wide women running shoesNike Air Max 1 Ultra Plush GrisNEW NEW BALANCE CLASSIC 574 TRADITIONNELS RUNNING SHOES **FLASHY** WOMENS SIZE 5 ,
"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."