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.Klogs USA Womens US 10 Med White Gray Marble Clogs Garden Rain Man Made ShoesKim Rogers Women's Size 6 Brown Clogs Slides Mules LeatherWomen's Skechers 14730/BBK Go Step Lite-Enchanting Black , Geox Moc Toe Loafer Women size 38/8 Brown Leather Embossed SnakeROS HOMMERSON Women's ODELLE Black Glitter/Patent Ballet Flats 8.5M (74014-06)EUC DANSKO WOMEN'S PROFESSIONAL SLIP-ON CLOG BROWN OILED LEATHER 39/ 9 MEDIUM , Traditional Women Shoes Leather Flip-Flops Handmade Juti Indian Oxfords US 4-12 , NEW WOMENS HUSH PUPPIES ONIKA BLACK LADIES LEATHER CASUAL COMFORT SHOES , Ladies Strap Fastening Leather Cushioned Back Casual Comfort Women's Shoe , SANITA PROFESSIONAL SIZE 36 BROWNS IN NEW CONDITION LEATHERCrocs Women's Lina Graphic Ballet Flat Leopard Size 5EUC ! **TROTTERS** Bone, Leather Basket Weave Loafer, Shoe, 3/4" Heel, 7 M , DR. COMFORT WOMENS cathy SHOE **NIB** SZ 7 1/2W , Fergalicious Women's Mizmatch Sneaker, Black, Size 7.0Adidas Womens Adilette S78838 Rita Ora Size 6 Us , Vera Wang Lavender Leather Ballet Flats Green with Rhinestones 7.5 , 13817 Skechers Performance Womens On-The-Go Retreat Shoe Black , Adidas Neo Raleigh Womens Mid High Top Sneakers Gold Size 8New Balance Womens 870 V3 Mesh Revlite Pink Running Cross Training Shoes 6.5 B , MENS SIZE MEDIUM 8-9 NORTHERN TRAIL BLACK WHITE PLAID SLIPPERS SHOES NEW SH112 , Nike Benassi JDI Fanny Pack Slide Black Cool Grey Summit White Gray AO1037 001 , Nike Jordan Hydro 7 VII 14 XIV Black Red Men Sports Sandal Slides AA2517-003Pre Owned Pink Nike Flyknit Lunar 3 Athletic Running Shoes Womens Sz 9 Fast Ship , Fashion Blue Tennis Breathable Mesh Sneakers Running Shoes for Women- US Size 10 , FOOTJOY 98647 eComfort Wo's 7.5M Tan White Golf Shoes LNC , The North Face Womens Sz 7.5 Hiking Walking Athletic Sneakers Shoes (F11)Nike Womens Free RN Flyknit 2018 Shoes 942839 001 Black/White Size 6.5 , All Star Converse Ox Blue Denim Floral Print Sneakers Shoes Women's Size 12 NEW , Women's Cushe Boots Allpine Tundra Dark Brown/Purple UW01905 Brand New!!!BROOKS Pure Grit Womens Running Hiking Shoe Size 9 Black blue purple
"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."