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.EARTH SPIRIT SHOES WOMENS SIZE 7 MWomen's Size 10 Flats Shoes Floral Pink Bows (S24) , Spot On F8757 Ladies Black Patent Dolly Shoes , Women’s Clarks Shoes Brown Brazilian Leather Mules Sz 8 M Low w/Stitched Detail , Womens MERRELL Primo Seam nubuck leather slip on hiking mocs CLOGS sz 8 , CHAUSSURES FEMME MARQUE MONOPRIX POINTURE 41 NEUVES BASKET VILLE HABILLEES CUIRCute Skull & Crossbones Bow Tie Slip On Slipper Ballet Flats Shoes Adult Women , **Naturalizer Oath Pumps - Women's Size 6.5M, Leopard Print , Klogs Haley Display Model Shoes Distressed Leather Iron 9.5 MSpring! Vera Wang 7 ITALY Green Silk Heel Mule Rhinestone Fancy Shoes ECClarks Ladies Shoes - Indigo Charm , Proxy Womens palisades ll Closed Toe Mules, ba9, Size 8.0 Euzn , Women's Adidas Boost Supernova Running Shoe, Black/Pink, Size 7 , Easy Street Women's Kacey Flat, Navy/Flannel, 6.5 W US , L@@K! NEW WOMENS AUTHENTIC MERRELL KAMORI EDEN ATHLETIC SNEAKERS SLIDE SHOES 5 MWomen's LILAC / PASTEL PURPLE SUEDE PUMA - Size 8,5 US, 6 UK, 39 EU *RARE*REEBOK f/s hi classic shoe Girls Size 10.5Women's Dance Shoes Soft Mesh Breathable Sports Athletic Casual Sneakers Jazz , EUC Columbia Kaibab Shoes Womens US 9 Hiking Trail Sneakers Shoes Boots , Skechers Women’s Performance Go Walk Joy Miraculous Charcoal 15610/CHAR , Women's Women's Dawgs Ultralite Walkers Special Offer Athletic Shoes , **Drew Solo Mesh Sneaker - Women's Size 5 WW, Royal BlueBeautiful American Curl Cat Print Sneakers For Women- Free ShippingWomen's Brooks Glycerin 14 Running Shoes Anthracite Azalea SilverLE COQ SPORTIF Saint Malo Jer Noir , Nautilus Shoes N1391 Women's Composite Toe ESD Safety Athletic Shoes Size 7.5 MWomen's Nike LunarTempo Running Shoes NEW White / Black / Volt / Aqua, MSRP $110 , New Balance Women's Fresh Foam 822v3 Graphic Trainer Size 6.5Skechers Performance Womens Go Run 600 - Running Shoe- Pick SZ/Color. , Women's Asics GT-2000 Purple & Pink Running Sneaker (7) ,
"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."