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.Ralph Lauren RL Kristi 3 Flats Woman's SIZE 6B BLACKJutti Indian Mojari Leather Handmade Khussa Ballet Flats Women Shoes US 6.5/8.5Dansko Eartha Wine Suede Clogs Mules Women's Size 41 , Women's SAS Loafers Shoe Size 7.5N Beige Leather Kilt Tassels Tripad Comfort L12SAS SIESTA GRAY LEATHER SHOES TriPad Cushions SuperSoft Sole 10 1/2 MARIAT Clogs Floral Studs Detail Stretch Sides 2" Heel Women's 7.5 M Brown ShoesButterfly Twists Samantha Glitter Folding Flat Ballerinas Bronze Women’s Size 7Women's Steve Madden Sneaker Shoes, Whilma , Size 8 NEWNEW Ahnu Telegraph Slip On SHOES FLATS 10.5 41.5 $99 Retail Leather GreyHush Puppies,slip-on,silver,removable contoured insole,the body shoe,fashion , Ladies Clarks Shoes - Evianna Boasamples shoes BALLERINE ETNIES CHAMBOSA GRUNGE WHITE BLUE GREEN WOMEN , Nine West Womens Anastagia Suede Pointed Toe Ankle Strap Mary Grey Size 9.5 l1 , Womens Sneakers Indoor Cross Trainer Shoes (Tennis/Badminton/Pickball) Plus size , Skechers Womens 11860Ew Navy/White Walking Shoes Size 7.5 (2E) (362533) , Women's Athletic Shoes Casual Sport Platform Shake Sneakers Hollow Breathable , Mens Padders Extra Wide Fit Slippers - 'Peter' , Mens Four Seasons House Slippers 'Terence' , DOLCE & GABBANA Elastic Leather Slippers Shoes MILANO Sangria Red Bordeaux 05185 , Amputee Shoe Womens Sneaker RIGHT ONLY Leopard Print Stretch Pull-on Size 6 NEW , NIKE RIVAL D 6 White Pink Mid Long Distance Track Spikes Shoes NEW Womens 10.5Vionic Orthaheel 555 August Walking Fashion Sneakers Shoes Tan Silver Womens 8MREEBOK CLASSIC Brown Athletic Shoes Womens Size 7.5Adidas Womens Turbo 3.1w Lavender / Coral Running Training Shoes Size 7.5 AF6651Womens NIKE FLEX TRAINER 4 Running Trainers 643083 700 US 7 , PUMA Womens Vikky Swan Fashion Sneaker- Select SZ/Color.VANS Sk8 Hi Decon (Canvas) Dress Blues/True White High Top Sk8 WOMEN'S 9.5La Sportiva Womens Synthesis Mid GTX Athletic Trail Hiking Boots US 11 , New Kenneth Cole Womens Kayla Black Patent Fashion Sneaker Size 8 , Bloch Spark Jazz Shoe - Black ,
"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."