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.Trotters LIZ Size 6.5 N Black Basket Weave Woven Leather Loafer Career Shoes , NEW Womens SODA OBJECT Gray Slip On Fashion Loafers Faux Fur Casual/Dress ShoeUnisa Black Slide Alligator Shoes Womens 9.5 inv3097Hush Puppies Keepsake Womens Oxford Shoes Black Leather Retail $69.99Cole Haan Womens Brown Leather Horse Bit Loafer Size 6 Slip On Flats Style F8020LANDS END Slip On Zipper Quilted Nylon Red Suede Shoes Womens 7 86524 Bootie CS7Dansko Women's Black Leather Cross Stitch Loafer Clog Mules Size 37 /7 USTaryn Rose Womens Beverly Closed Toe Mary Jane Flats , Simple Hallie Suede Mule Slide Clog Casual Slip on Shoes Taupe Women's Size 7 MMinnetonka Women's El Paso II Suede Moc - Taupe - 7Isaac Mizrahi Amy Burgundy Red Pebbled Leather Driving Moccasin NEWWomen’s SIZE 7 ASICS GEL-FLUX 4 Running ShoesWomens Flat Horsebit Slip On Shoes Brogue Round Toe Retro Metal Decor Loafer TopNew New Balance Womens 555 Blue Walking Shoes Size 5.5 , New HUF Womens Hupper 2 Lo DeepWine Fashion Shoes Size 5.5ASICS Womens Gel Craze TR 3 Gray Training Running Athletic Shoes Sz 9 IP-72"Keds" Womens Navy Blue Tennis Shoes in Good Condition size 9 1/2 M , Women's Fashion Sneakers Canvas Floral High Top Flat Heel Casual Shoes SzAsics Gel Scram 3 Athletics Shoes - Women's Size 7 - BlackNike Free 4.0 v4 Gray Running Shoes Women's 10Keen Versago Hiking Shoe- Women's Size 10, Purple/ OrangeWomen's NIKE Lunarsolo Womens Running Shoes Bargain Price Athletic ShoesVans Off The Wall High Top Skate Shoes Geometric Aztec Embroidery Womens 6 36 , Navy Striped Rose Peony Lowers Leaves Women Boots Martin Boots For GirlCharolais Cattle Cow Christmas Running Shoes For Women- Free ShippingNew with tags Asics Gel Contend 2 Womens sz 8.5 running Shoes Teal, Coral, WhiteKenneth Cole New York Women's Kam Fashion Sneaker, Black Leather, 7.5 M USNike Air Max 749862-007 Invigor Print Pure Platinum/Metallic Silver Womens Sz 12 , Women's Skechers - RELAXED FIT: BREATHE EASY - WEEKENDER - Black - New!NEW! Merrell Outright Edge Womens Black/Lavender Sneakers size 11 J342286C ,
"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."