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.Sperry Top sider black and white striped shoes womens size10m 9776790. , High Sierra Brown Leather Split Toe Mules Clogs Heels Slides Shoes Womens Size 8 , Womens DANSKO Black Fabric Slip Resistant Slip on Loafers Womens Size 40 US 9.5 , Skechers 48930 Relaxed Fit Memory Foam Bikers Pedestrian Womens Size 6.5SKECHERS BOBS BLISS MARS SLIP ON SHOES WOMENS SZ 8 BROWN MEMORY FOAM EUC , Topical US 9 B Red Wine Suede , Easy Spirit Gorsky Espadrille Flats, Medium Red/Medium Red, 8.5 W USI35 Zachh Cross Strap Ballet Flats, BlackNine West Flats Womens Size 7 White Leather Open Toe Open Side Slip On-5622AMANDA BROWN SHOES WOMENS SIZE 7 1/2 M , Clarks Women's Keesha Cora Casual Shoe , NEW!!! Easy spirit woman casual flat animal print size 9.5 MGRAVATI Women's Shoes Brown SUEDE Loafers size 8 US2018 Women's Sports Running Shoes Mesh Breathable Casual White Sneakers Shoes , La Redoute Collections Womens Daisy Detail Ballet Pumps , New Womens Skechers Synergy 2.0 Simply Chic Shoes Style 12379 Black/White 80G pr , Nike Free 5.0 Running Shoes Women’s Size 8.5 US Excellent Condition , Asics Aqua & Pink Mesh Athletic Running/Walking Sneakers Shoes Size 7.5! , Skechers Women's Super-Cup - Magnolia Casual Shoe , New Propet Womens W2035 Black Fashion Sneaker Size 5 (C,D,W)Reebok Women's Gray Green Neon Athletic Running Shoes Sneakers Size US 7.5Women's Nike Woman Shoes 9.5 Low-priced Athletic ShoesNew Women Vans Old Skool True white Skateboarding Shoes Classic Canvas size US 6Brand New with Tags Dr. Scholl's Women's Everest Gel Cushion Athletic Shoes,Gray , Asics GT 2000 V4 ? T656N?2039 - Women's Size 8, Pink & Indigo , Nike Womens 11 Shoes Platinum White Zoom Condition TR 852472-002 MSRP $90Skechers Sport Womens Spectrum Showy Fashion Sneaker- Pick SZ/Color. , Nike 472483-201 Air Rlty Royalty Highness VT Fashion Sneakers Women's US 7.5 , Zee Alexis Womens Danielle Athletic Shoes Black Teal Multi 7 M , New SKECHERS Slicker Leather Suede Women Shoes Size 10
"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."