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.Audrey Brooke Mules, 9 1/2, Cute & Comfy - FREE SHIPPING , Isaac Mizrahi Fuschia Pink Andreya Flower Slip on Cork Mule Clogs 6 NewVionic Chill Mesa Orthotic Suede Moccasins w/ Chain - Dark Grey US 5 |Women's Dansko black leather chunky heeled loafers slip ons sz 38 (7.5-8 U.S.) , Dr. Martens 8065 Double Strap Mary Jane Womens Shose Size US 6 , Women's COLE HAAN Black Loafers 7.5B Leather Shoes Silver Charm Moc Toe Flats , H by Halston Ballet Flats Slip On Bow Brown Black Leather Women Size 7 MediumMARCO TOZZI Ballerina Slipper Shoes Pumps Brown NEWCOLE HAAN Pinch Marine Classic Brown White Leather Penny Loafer Women US 6.5Charles Keith Satin Flats With Bow Detail - Blue, 36/37Womens Breathable Athletic Sneakers Casual Running Sport Shoes Outdoor Creepers , Nike Women's size 6.5 Athletic ShoesSkechers Campers Casual Shoes, Natural/Pink, Womens US Size 6.5 , CLARKS Women's Sillian Cala Mary Jane Flat, Light Grey, 7 M USsummer sweethearts wire side gym shoes arder shoes running shoe YY217 , ASICS Womens Gel-Venture5-W Blue Running Shoes Size 9.5 (333837)The North Face Women’s Sneakers Shoe Size 9.5 M running Orange Gray , SKECHERS Women's 12154/BBK Mystics Training Shoes.Womens Hi-Tec Penrith Mid Walking Waterproof Ankle Boots Hiking Trainers US 5-10Women's Women's Adidas SUPERSTAR SLIPON Sneakers-S81338 Customers First Athletic ShoesWomen's NEW MANGO WOMENS PATENT LOAFERS Beautiful In Colour FlatsMizuno Wave Tornado 5 Shoe - Women's Volleyball, SKU 430128.0090, Size 11.5 , Converse Womens Size 8.5 Pro Leather LP Scale Low Top Snake Black Shoes Sneakers , [881105 401]? WOMEN'S NIKE AIR MAX 90 SE NO BOX TOPWomen's Nike Shox Navina Metallic Silver / Bright Violet Running Shoes (6.5) , NIKE Free RN NWT BOX W/O LID Motion 2017 Flyknit Womens US 8 / RRP $220CONVERSE Chuck Taylor Eyerow Cutout Limestone W9.5 , SPRING COURT Women's B1 Linen White / Silver Canvas Sneakers Shoes US 6 / 37 NEW , Merrell Womens Siren Edge Waterproof Vibram Athletic Trail Hiking Shoes Size 9 , Easy Spirit Women's Romy Walking Shoe ,
"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."