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.Dansko Eartha Brown Suede Sweater Cuff Slip On Clogs Shoes /US 8.5-9 , G.H. Bass & Co Sandra Navy Canvas Oxford 10M , Ladies Spot On Casual Pointed Toe Loafersgloria-33 Fashion Flats Slip On Casual Office Party Wedding Prom Women Shoes Redsami-27 Slip On Casual Party Flats Office Winter Warn Women's Shoes Brown 7.5^BASS Womens Brown Leather Low heel Clog Mule Slip On 9MNEW FitFlop Superskate Sneaker, Supernavy Suede, Women Size 8.5 (40 EUR) $130 , Easy Spirit Derely Slip On - Women's Size 8.5W Black , Nine West Evadne Flat - Women's Size 9.5M GrayNew Women's Skechers 13522 Go Walk Everyday Ballet Flats - Navy Size 6 (Z2)Fashion Mens Women Leather Casual Running Sports Boat Flats Sneakers Shoes XW2Womens Tennis Shoes Ladies Casual Athletic Trainer Sports Sneakers Size US5-US13 , Womens Hidden Wedge Heel Sneakers Tassels Round Toe Shoes Beads Bowknot Hot size , Brand New Donald J Pliner Perly Beaded Nautical Loafers Ladies SZ 8B~Classic~ , WOMENS NIKE DUAL FUSION ST SHOES GRAY/PINK US 9Ladies Wedge Hidden High Heel Suede Sneaker High Top Ankle Boots Crepper Shoes , HOKA One One Conquest 2 Women's 8.5 (40-2/3) Running Athletic Shoes Grey PurpleMerrell Women's Moab 2 Ventilator Hiking Shoes 9.5 Ortholite Taupe Water ProofNike Roshe Flyknit Blue Women's Sz 9.5 , WMNS REEBOK PLUS RUNNER WOVEN WHITE SKULL GREY BS8379 DEADSTOCK BRAND NEWNIKE Womens Sz 8.5 Athletic Sneakers Running Shoes White Mesh Fabric LeatherWOMENS ADIDAS CC SOLUTION in colors BLACK / NEIRME / ULT GREEN SIZE 9 , Nike Womens Downshifter 7 Running Trainers 852466 Sneakers Shoes 010MBT 'Chakula' Womens Fitness Shoes Birch Leather Mesh / US 9-9.5Reebok Womens Fury Adapt Graceful Fashion Sneaker 5- Pick SZ/Color. , Asics Neon Yellow GEL-OS Athletic Running Walking Training Shoes Women's 9.5ASICS Gel Lyte Komachi Women's Peach Beige/Peach Beige Sneaker 7M , DS Brand New Women’s Nike Flex Experience RN 3 Sz 8Baskets Femme samples shoes ETNIES CHAMBOSA WHITE GREEN RED WOMEN , EUC Merrell J35750 Siren Edge Black Purple Women Hiking Trail Shoe US 8 ,
"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."