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.Kalso Earth Shoes SOLAR Mary Jane Flat Womens Size 7B Brown Leather , Yellow Multi Floral nn Point Toe Fashion Women Ballet Flats Dress Shoes Size 8.5 , Laforst Women's Black Leather Slip On Flat Shoes US Size 7Trotteurs MARCO TOZZI en cuir noir froissé, TAILLE 40LANDS' END FLAT SHOES FLORAL DESIGN PASTEL COLORS SIZE 6 , Ballerina flat by Miz Mooz (Parvati), black color, 6US/36EUSoftSpots Women's Haddie Slip On Clog Shoes Black Size 7MSteve Madden Exsess Loafers Pewter Metallic Women's Slip On Shoes Size 8.5B , New ARAVON Helena Bronze-Brown Patent Leather Office Slip-on Shoes 9.5 , Clark's Artisan Tona Reach Women's Brown Mary Janes Slip On Shoes Size 7.5 MPRIX SACRIFIÉ: BALLERINES NEUVES, 39,5, 100% CUIR, VERNIS GRIS IMPRIMÉ "PYTHON". , LADIES RUNNING AIR TRAINERS JOGGING GYM WOMENS SHOCK ABSORB SHOES BOOTS SIZESSt. John Sport Leather & Suede Loafers Size 9 Tan Beige Womens Shoes Career , Easy Street Genesis Loafer Flats, Brown , Brooks Ghost 8 Gray Running Shoes, Women's Size 9.5ADIDAS CrazyMove Studio BB1590 Yoga Dance Training Minimalist Shoe Sz 7 RED , Keds, Red & White, Womens Size 9 , New! Women's Skechers Air High Running Shoes Black/Pink SZ 6.5 12101 H31La Sportiva Womens Bushido Athletic Outdoor Trail Running Shoes US 8.5Adidas Women's Size 9.5 () Driver Lucy Fit Foam Golf Shoes Black Slip On EUC , Via Spiga Womens Marlow Heather Grey Jersey Walking Shoes Size 6 (22775)New Shimano Womens Rp2 Cycling Cleats Size 5.5Merrell 1six8 Heathered MOC AC+ Women's Size 7 High Rise 25%OFFWomens Nike Roshe Two Flyknit V2 Black Multi Size 10 917688 003 Running ShoeCamper Right Nina 21595 Grey Black Womens Leather ShoesNike Air Max 90 Womens Size 5 Green Gray WhiteWomens Adidas Vigor Trail Running Hiking Shoes Black Blue Teal Size 11Skechers? ~ BURST DIVERGENT DEMI Black Shoes ~ Everyday 12730 ~ Women Sz 9.5Nine West Women's Palyla Fabric Fashion Sneaker, Black, Size 8.5Diadora Mythos Magnitude Trainer Shoes - Womens 8 - Silver/Pink - NEW ,
"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."