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.Women's fessura Mummy Shoes Army Green Brown Mix Wrap Comfy Size 35 USA 4 5Gabriella Rocha Women's Black Rose Flat 8MH&M Ballet pumps with lacing 39 | BNWT , CHEEKS BY TONY LITTLE EASYSHAPERS WALKING MULE SHOES BLACK WOMEN'S 8 M , Propet Leather Sand SAPPHIRE Mary Jane--size 11WRockport Red & Black Snakeskin Leather Comfort Loafer Ballet Flats Size 10MClarks Leisa Ruffle Slip On Front Cut Out Slide Flats 300, Brown, 9.5 US / 41 EU , club monaco Vero Cuoio Women’s Flats Shoes Size 38 Black Glitter Slip On Italy , **Easy Spirit Barton Loafers, Women's Size 6.5, Black , Sperry Top Siders Womens 7.5M Vintage Boat Shoes Gray Neon Green Leather P109 , Kenneth Cole New York Willow Ankle Strap Flats, Rose, 7.5 US / 38 EUCORSO COMO PYTHON BALLET FLAT WOMENS NUDE CALF US SIZE 9.5 MEDIUM NEW W/O BOXLA Gear white athletic shoes size 9.0 Men’sVINTAGE 2007 WOMEN'S ECKO PHRANZ PHANCY 26249WNT WHITE/NATURALECCO WOMENS COMFORT WALKING OFF WHITE LEATHER ATHLETIC SNEAKER US 8 - 8.5Nike Dual Fusion ST 2 Womens Running Shoes Size 6M Blue Waffle Sole- 4545 , Brooks Glycerin G13 Purple Grey Teal Athletic Running Shoes Women's Sz 10 , NIKE Women's W Air Max Thea Ultra PRM Summit White/Summit White-Summit Size: 5.5Women's Ellie Women's Viking-433 A Complete Range Of Specifications Athletic ShoesBrooks Addiction Walker Walking Shoes - Women's Size 7.5B, White (DAMAGED)Vans Women’s Sk8 Hi Slim Dabs Maya Multi Black Sz 9.5 NIBSalomon XA COMP 7 Women's Grey Denim/Stone Blue/Lucite Running Shoe 7.5M , 'Freedom Unicorn' Running Shoes (Men/Women)-Free Shipping , Womens ADIDAS SPRINGBLADE Running Shoes sz 9 Athletic D66233US:7 adidas Originals Women's FLB RUNNING SHOES *RUN 1/2 BIGGER FIts 7.5*Nike Women Clean Jade/Black Air Huarache Run Mid Leather Shoes NWOB Size US 8.5Salomon X Ultra Women's Peacock Blue/Deep Blue Hiking Shoe 7MEuropean Womens Girls Round Toe Platform Tassel Athletic Sport Casual Pump Shoes , Asics Unisex Sports Leisure Trainers WhiteKeds Women's Chillax Floral Eyelet White Slip-On Shoes-Sizes 7/7.5/8/8.5/9 -NWB ,
"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."