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.Polo Ralph Lauren Women Frabric Canvas Deck shoe Beige Pink Flats Slip On 6.5BSpot On Ladies Flat Shoes White F80014 X 8 (R3B)Womens GH Bass & Company Brown Slip On Moccasin Style Shoes - Size 7.5SAM EDELMAN Felicia Women's Gold Leather Slip On Ballet Flat Shoes Size 6.5 MDr. Scholl's Leader Pointed Toe Flat - Black - 10 MDr Comfort diabetic shoes...Mary Jane Size 9 , Steven By Steve Madden Womens Boyhood Platform Loafer ShoesClarks Nikki Regatta Navy Blue Leather Fisherman Shoe 6 NewBruno Magil Brown Suede Size9 WomenAnne Klein Women's Daneen Black Leather Slip-on LoaferEnzo Angiolini Womens Lianne Closed Toe Loafers Black Size 8.0 8uUy , Bass Weejuns Womens Washington Leather Tassle Slip On Loafers Burgundy Box Sz 6Eastland Womens Aquarius Slip-On Loafer- Pick SZ/Color. , Keen Womens H2 Newport Sandals Waterproof Size 6 Anatomic Footbed Preowned Good , Acorn Rambler Moc Slipper - Men'sWomens The North Face Hiking Trail Sneakers Shoes Gray US 9 /Skechers Sport Women's Crafter-Gnome Patrol Clog,Toffee Brown Size 6.5Women's BALLERINES MERLET MOD.ADELE NEUVE VAL.!!!!!!! Diversified Latest Designs FlatsReebok Women's Classic Renaissance Walking Shoe - Choose SZ/Color , NIKE ROSHE ONE PRINT Size 8 (844958 800) EMBER GLOW BLACK WHITE WOMEN SNEAKER7 WOMEN'S NIKE HTA RUNNING TRAINNING CASUAL BLACK WHITE COMFORTABLE LIGHT 5.5YAdidas Women's Originals Tubular Viral2 W Utility Black/White BY9745 - BRAND NEWNew Balance WPACEYB D Wide Yellow Green Silver Women Running Shoes WPACEYBD , KEEN Womens Terradora Mushroom/Magnet Hiking Shoes Size 6 (9693)Skechers Performance Women's Go Flex Slip-On Walking Shoe - Choose SZ/ColorMizuno Maximizer 19 Black/White/Pink 2017 Basic Wide Running Shoes K1GA170101Nice Blue Silver White BROOKS Adrenaline 11 Running Shoes US Sz 9BWomens SKECHERS 11807 SHAPE UPS Black Mary Janes Walking Shoes SIZE 8 , Teva Freewheel Corduroy Casual Shoes - Women's Size 7, BlackMEPHISTO ALLROUNDER Beige Suede Mesh Sporty Mary Jane Walking Shoes Size 9
"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."