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.Jambu All Terra Black Maryjanes Size 6 Mellen tracy cynthia 40 9 womens ladies loafers black peep toe wedge buckle flatsNickels Soft Black Loafers Comfort Shoes Sz 5.5 WomensKeen Cush Slip Ons Purple suede Loafers Size 7 , Sanuk Women's Espie Slip On LX Espadrille Size 9Propet Women's TravelFit Flex Ballet Flat, Watermelon, 12 2E US , Chinese Laundry Womens Eternal Love Pointed Toe Slide Flats Taupe Size 8.0 2g5 , Clarks Womens Size 10M Brown Basketweave Leather Slip On ClogsPrada Black Leather Women's Peep Toe D'Orsay Flats Size / US 8 , SANITA PROFESSIONAL SIZE 36 BLUE PATENT IN PRISTINE CONDITION LEATHER , ORTHOFEET Orthotic CHATTANOOGA MARY JANE Black Shoes Womens Size 10.5BHush Puppies Women's Basel Audra Slip-on Loafer, Smoke Nubuck, 9.5 W USHARAJUKU Lovers Size 6.5 Yellow Graphic Sneakers Shoes This Love Is Serious , New Women's Skechers Slip On Athletic Casual Shoes 22406EWR Bungee SIZE 7 , Womens Skechers Relaxed Fit Air-Cooled Memory Foam Slip On Shoes Cream size 7.5Nike Air Prestige Women's Size 9 White Yellow Orange Shoes Sneakers , Nike Free Run 3.0 V5 Black/White Women’s Sz 6.5 Racer Training RN 5.0 Flyknit , Reebok Zig Nano Women's Gray Pink Athletic Running Training Sneaker Shoe Sz 7.5FILA RAY Disruptor Fashion Sneakers For Women's Shoes FS1SIA3063X White Pink , Nike Presto Faze 2001 Women’s Black White Silver Women’s Size Medium , Saucony Women's Excursion TR11 Running Shoe - Choose SZ/ColorTidewater Sandals Women's Boca Slingback Sandal Navy/Natural Slingbacks , Under Armour Women's Speedform Slingwrap Sneaker, Blue, 9 , Dirty Laundry Womens Just Right Fabric Low Top Slip On, Black/ Mult, Size 8.0 iSCONVERSE WOMEN'S CTAS GEMMA OX 554429C WHITE/MOUSE/WHITE RARE! SIZE 10 EUC , Woman's New Balance 608-V4 White & Purple Training Shoes Size 8.5D , Ecco Receptor RXP 3040 Running Sneaker-Training Blue/White Shoe Women 10/10.5Ryka Women's Noomi Running-Shoes - Choose SZ/ColorSkechers Women's Go Run 600-Spectra Sneaker - Choose SZ/Color , Moxie Trades Women's Robin Aluminum Toe Composite Plate Work Shoe Black/Pink 9.5 ,
"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."