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.Pre-Owned Bar III Zero Black Slip On Flats With Gold Bow Accent 7.5M , Cute Demonia Shiny Pearlized Pink Glitter Leopard Ballet Flats Size 6, NEW , Lifestyle Ladies Size 8 Light Blue Leather Loafers New in Box , Cole Haan Air Womens Morgan Pink Suede Green Trim Slip On Ballerinas Shoes 5B , TEVA KIRU T 6086 Womens Leather + Wool Slip On Shoes 9MZara Woman ombre metallic silver gold glitter pointed toe ballet flats shoes 6.5 , Women Bow tie Flats Shoes Soft Boat Ballet sapatos para mujer US 8 9 10 11 12 13 , Klogs Haley Clogs Display Model Shoes Leather Black 7 MNEW SPERRY TOP-SIDER COIL IVY PERF WOMENS AQUA LEATHER BOAT SHOE/ STS99178 $90ASICS Gel-Kanbarra 5 White/Lightning/Apple Green Women's Athletic Sneakers 8MTIBER-18-39 WOMEN SUEDED STUDDED BOOTIE QUPID WINE SUEDE PUDemonia Drac-03 Black Velvet Ribbon Flat Shoes - Gothic,Goth,Punk,Black,Buckle , Womens Cabelas Slip On Moccasins Shoes Black Suede Size 8MAXAIR Run Shoes NIKE ~ Everyday 312046-141~ Women Sz 7.5 ~ GOOD , Converse Women's Beige Woven Slip On Athletic Flats Size 7.5Danskin Now Black & Purple Ladies Memory Foam Athletic Slip-On ShoesWomen's Trotters Women's Samantha Ballet Flat Aesthetic Appearance Flats , Saucony Omni 12 10207-2 Women's Gray /Purple / Citron Running Shoes WIDE Widths , Nike Tanjun SE Womens 844908-303 Vintage Green Mesh Running Shoes Size 7 , Pacific Trail Pumice Sandals Women's Shoes , Vibram Womens Trek Ascent Five Fingers Minimal Trail Running Shoes Size 36Brooks Womens Ghost 10 Black Running Shoes Size 8 (C,D,W) (36160)Brooks Revel Running Shoes-Women's size 12B White/Black , New Nike Dart 10 Women Running Shoes Sz. 11.5 - 580427-402NEW! PUMA 186896-06 Womens Lady Bioweb Elite Red/Blue 8 105K aa , ADIDAS Women's Cloudfoam QT Racer Sneaker Navy Blue 7.5ASICS Women's Gel-Torrance Running Shoe Purple/White Size 7 , New Balance Womens - Gray Walking Shoes Size 8 (415801)Bronx Women's Zoo Nee Fashion Sneaker,Natural,39 EU/9 M USNew Balance Womens WL555BA Gray 555 Fashion Sneakers 5.5 Medium (B,M) BHFO 9729
"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."