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.Sesto Meucci Women's Driving Shoes Mocs Horse Bit Croc Print Brown Leather Sz 7M , CROCS Womens 12347 Berryessa Flats 8 Blue Suede Faux Fur Insoles Driving ShoesLadies Shoes Inniu Bobbi Ballet Flats Taupe or Black With Bow size 5-10 New , Tsonga Shoes Leather Mules Chunky Heel Slip On Style Clogs Fall Fashion Size 8 , Ollio Women's Ballet Shoe Comfort Luxurious Accent Multi Color Flat8 BM US Kh... , CROCS "Janya" Closed Toe Slingback Shoes Matte Black w/Teal Trim Women's Sz 8SAM EDELMAN Shoes 8 M Patent Leather Pointy Toe Wedge Slingback S-Ionia CoralCole Haan Womens navy blue suede loafers driving shoes sz 7 B , Kenneth Cole Womans Flats Size 7 Black Leather Mary Jane Wedges , Keds Womens double decker quilt Closed Toe Mules Grey Size 6.5 u637New Foot Pedal Womens 71242 Gold/Multi Walking, Hiking, Trail Shoes Size 11Bordello Women's Teeze 04G , NWT $50 Crocs Isabella Wedge Comfort Sandals Shoes Women's Size 11 Coral Pink , SANITA Laguna Life Mesh Mary Janes Slip On Women Shoes Size Euro 41/ US 10 EUCNike Air Vapor Advantage Athletic Women's Shoes Multi-Color úS Size 7Skechers 12013 Women's Front Row Fashion Sneaker, Gray/PurpleSkechers Sport Women's Flex Appeal2.0 Mixed Media SneakerBlue9 M US , New Reebok Womens Walk Ultra V Dmx Max Pr-White/SolarPink Walking Shoes Size 7 , Men's Shoes Slippers MEN'S BUD LIGHT SLIPPERS Aesthetic Appearance Slippers , Ryka Women's Kailee Slip On Sneaker Blue/Grey Mesh/Synthetic Sneakers , ADIDAS AQ0886 TUBULAR SHADOW CK Wmn's (M) Black/Shock-Pink Knit Athletic ShoesAsics GT 2000 Running Shoes Women’s Size 8.5 US Near Mint Condition @@Asics Gel-Kayano 23 Running Shoe- Women's Size 8, Safety Yellow/TurquoiseWomen's Nike Marxman Premium Lifestyle Shoes NEW in PinkNike Women's "Fi Impact" White - Orange Golf Shoes Size 7 NewSteve Madden Black Satin Glamour Platform Sneakers Pearl Rhinestones. New $90 , Merrell Women's M-Connect Series Black/Teal Running Shoe Vibram - Size 8Nike Lunarsolo Womens Style : Aa4080VANS Shoes 935991 Blue 23.5 , Keds Champion Sneaker - Women's Size 6.5 Gray ,
"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."