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.Rialto Annalynne Ballet Flats 602, Black Patent, 10 USIsaac Mizrahi Lori Snake Embossed Bow Detail Ballet Flats Medium Honey 6 1/2 M , New In Box Soda "Object FS w/Sherpa Lining Flat Shoes Loafers, Size 7, WineRed & Black - UNISA- Dressy Sandal - 9 ½ , NEW LIPSTIK LIPSTIK TOFFEE BLACK SANDALS , Sam Edelman Alaine Animal Print Calf Hair Scalloped Ballet Flat 6.5Kelsi Dagger Brooklyn Loafer Nude Snake Collapsable Back 7m , Clarks Womens Esha Marigold Black Leather Slip-on Loafers Shoes Sz 8 1/2M w/Box , J Crew Silver Leather Anya Ballet Flats Shoes Size 7.5 Metallic E5003CROCS Dual Comfort Lightweight Sarah Floral Slip On Mule Clogs Women's New 11 , WOMEN'S MINNETONKA 402 KILTY BROWN MOCASSINS SUEDE , J - 41 Womens Sz 41 Clogs Loafers Fashion Shoes Black Leather (G16)Jon Josef Women´s Paloma Gold Leather Espadrille FlatsTalbots Womens Flat Sz 7 M Navy Blue Suede Leather Calf Hair Tassel Loafer ShoesNike Metcon 2 Women Sz 7.5 White And Teal Training Shoes**Skechers Flex Appeal 2.0 Training Sneaker - Women's size 7 - Gray/Pink , Nike Flex Trainer 5 Womens 724858-001 Black White Size 6.5Women Platform Hidden Wedge Loafers Sneakers Slip On High Heels Shoes sbox1 , Delman 7.5 Gold Metallic Loafers Flats Great condition made in Spain leatherSONOMA Fae Black Leather Life & Style Slip On Clogs Women's Size 6 , Mens Gents House Slipper Shoes Moccasins Memory Foam Plain Slip On Fur Loafers , Women Asics GT-2000 5 silver purple blue athletic running shoes, sz 8.5BROOKS Adrenaline GTS 17 Running Shoes, Women's Size 6 , Converse All Star Chuck Taylor Layer Up Plaid Hi 111159F Mens 9 Women 11 Shoes * , Women's WOMEN'S H&M’s CASUAL SHOES-SIZE: 7 Outstanding Features Athletic Shoes , Valentine's Day Special Boston Terrier Print Running Shoes For Women- Free Shipp , Mustang Slippers Trainers Sports Shoes Low shoes light grey Canvas 1099 NEW , Brooks PureFlow 5 Lightweight Running Shoes, Women's - Size 7.5 B, Black/Pink , Skechers womens Shape Ups Sneakers Black, White & Pink Sz 8.5 (LR) , NWT Skechers Alba Winter Street Womens Shoes Boots 10 White MSRP$70
"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."