Presence of salty water- conducive to support life of microbial organisms that emanated billion years ago on Earth- has corroborated the thesis that Mars can also support life, avowed the researchers on Monday.
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.
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 percent,” Stamenkovic said.
By comparison, the life-giving gas makes up 21 percent 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 hotsprings — 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.
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.
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 degrees Celsius (minus 319 to 68 degrees Fahrenheit).
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.
“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.”