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.Kelsi Dagger Brooklyn Adly Lizard Embossed Leather Mule Size 7.5 Platinum , "Stuart Weitzman" Clogs Brown Suede Slip On Mule Women's Shoes Size 7 non slip!NEW Aerosoles Filmore Womens 8 M Leather Slip On Comfort Flats Oxfords ShoesLight Pink Ralph Lauren Ballet Flats 7M , SOFT WALK BROWN Fabric Faux LEATHER SLIP-ON COMFORT 7.5 WW (S1282-200) Rtl $149 , Kenneth Cole New York Women's Shoes Beige Penny Loafers Sz 6 Heel Made in Italy , Clarks Cloud Steppers Woman"s Size 9m Red and BlackJOIE Huxley Women's Size US 5 / 36 Slip On Sneakers Black Perforated Laser CutSteve Madden Womens Black Slides Flats Size 7.5Fergalicious Women's Jiffy Sneaker, Black, 8.5 M USTorrid Womens Flats Size 8 Burgundy Silver Bling Embellished , NEW Rockport M77932 Coralee Canvas Sneakers, Women's Red - Choose Your SizePUNK WOMEN'S LADY RIVET PEAL REAL LEATHER SLIPPER PUMPE SLIDE MULES ROMA SANDALSTraditional US 6-12 Indian Women Shoes Designer Blue Mojari Ballerinas , Women’s Dansko eu size 36 US 5.5 dark gray Purple Leather Tennis ShoesNew Navy Blue Dansko Leather ballerina shoes. sz8. RT$99.+ , Right Foot Shoe Converse All Star Grey Size 11 Amputee Ship Fast! , Fabletics Zuma Studio Sneaker Size 10 , Saucony "Runanywhere" Black and Hot Pink Running Shoes Women's 8.5Women's NIKE Rosherun Print White Blue Online Sale Athletic ShoesWomen's BCBGeneration Sabrina Flat Mules, Taupe Moderate Price FlatsSuperga Women's 2750 Fglycrau Sneaker - Choose SZ/Color , Topo Halsa Running Cross Training Athletic Shoes Sneakers Lime Orchid Womens 7Nike Womens Air Huarache Running Ultra Gamma Blue Sneakers 833292-401 Size 8 , Saucony 9M Triumph Iso 2 red black running womens ladies running sneakers shoesAdtec Women's Composite Toe Uniform Athletic Boot Black Size 6.5 , Zara Women High Top Suede Sneakers W/Zip Black casual shoes size US 6.5 , Womens Topo MT2 3mm Drop Athletic Trail Running Shoes Size Right 6.5 Left 7BROOKS TRANSCEND Pink Running Athletic Sneaker Shoes Women's Size 7 , Asics Gel Kayano 24 Purple Pink Mesh T799N Running Shoes Women's size 6 / 37
"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."