Salty Water Beneath Mars’ Surface Could Contain Enough Oxygen to Host Simple Animal Life

A new study proposes that salty water, which lies just beneath Mars’ surface could contain enough dissolved oxygen to host microbes, and maybe even simple animal life like sponges, in certain areas.

An exciting development for Asgardia as they work toward building habitable platforms in low-Earth orbit.

These surprising results could help scientists’ reform their understanding of the Red Planet’s habitability, both from the past and currently, according to study team members.

Author Vlada Stamenković, a research scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California, explained that these are exciting times, in particular, because there is so much more work still required, to learn more about Martian habitability. Stamenković added that they hope thinking of Mars as a potential place for life to exist, maybe even today creates excitement in the scientific community and the larger world.

Results from spacecraft including NASA’s Viking orbiters, the Mars Reconnaissance Orbiter, Curiosity, Spirit, and Opportunity rovers have shown that water flowed freely across the red dirt of Mars in the ancient past. Many scientists believe the Red Planet even had oceans billions of years ago.

However, the water on Mars’ surface vanished long ago, after the Red Planet lost most of its atmosphere and transformed into the cold, dry world we currently see. Researchers think that some wet stuff probably persists underground today — in deeply buried aquifers and in salty brine pockets, some of which may sit just below the surface.

For instance, certain scientists believe the seasonal Martian dark streaks called recurring slope lineae are a result of the escape of such brines, which can remain liquid at much lower temperatures than “pure” water due to their salt content.

Stamenković and his team modelled the potential for oxygen-harbouring of near-surface brine reservoirs, calculating how much dissolved O2 they could hold at various regions around the Martian planet.

Life as we know it doesn’t necessarily require oxygen; the earliest Earth organisms were anaerobic, and so is a massive chunk of our planet’s modern microbial diversity. However, oxygen is such a vibrant energy source that when it is present, it makes many interesting evolutionary pathways possible, including the rise of complex plant and animal life. (Almost all known multicellular species on our planet breathe oxygen in some manner.)

The researchers also discovered that Martian brines could contain a lot of oxygen — enough to support aerobic microbial life almost everywhere if the requirements of these hypothetical Mars bugs mimic those of Earth. And the models demonstrated that dissolved-oxygen capacity varies greatly both over time and from place to place, since it depends on temperature and, to a lesser extent, pressure. (The temporal variation is tied to shifts in Mars’ obliquity — the tilt of its axis of rotation.)

The colder the temperature, the more significant the oxygen entry is into the brines. So, more frigid pockets near the Martian poles could be oxygen-rich enough to support complex multicellular organisms like sponges, as per the research. Such “aerobic oases” might be familiar today above 67.5 degrees north latitude and below 72.5 degrees south latitude.

Thus, Stamenković explained that astrobiologists shouldn’t overlook cold environments just because relatively warm ones tend to be better for life as we know it here on Earth.

Stamenković added that each environment has its own pros and cons. There is some observational evidence to support the new modelling results. For instance, the Curiosity rover has detected manganese oxides during its exploration of Mars’ 96-mile-wide (154 kilometres) Gale Crater.

What’s more, Stamenković said it takes a lot of dissolved oxygen to generate these minerals. On Earth manganese oxides formed only after O2 began persisting in the atmosphere about 2.5 billion years ago — what’s known as the Great Oxygenation Event (GOE).

The researchers model shows that manganese oxide formation can happen on Mars, because of the briny environment and the low temperatures.

The GOE came with the rise of oxygenic photosynthesis, which produces virtually all of the oxygen in Earth’s air presently. There’s only a small amount of abiotically generated oxygen in Mars’ air, but that doesn’t mean that none of it can make it into buried brines. For example, on top of the atmospheric trace oxygen, radiation given off by radioactive elements in Martian rocks could split water molecules into their constituent hydrogen and oxygen, according to Stamenković.

In fact, radiolysis and/or other processes may have been vital for almost all of the Red Planet’s history, raising the possibility that Mars life — if it was ever-present — has had access to energy-rich oxygen for billions of years. The same could also be true on other worlds with freezing habitable environments, like the buried-ocean moons Europa and Enceladus (which orbit Jupiter and Saturn, respectively), stated Stamenković.

He also explained that there are so many abiotic ways of producing small but sufficient amounts of oxygen which then, at the colder temperatures, can be absorbed adequately, and could actually potentially prompt evolution in a different way than what we saw happen on Earth. However, Stamenković noted that this is all hypothetical, but worth looking into.

Both NASA and the European Space Agency (in conjunction with Russia) have plans to launch life-hunting rovers to Mars in 2020. Both of those robots will be hunting for signs of past life. The last, and so far only, spacecraft to look for present-day Red Planet organisms on the Martian surface were NASA’s twin Viking 1 and Viking 2 landers, which made it to Mars in 1976.

Although Stamenković would like to see that to change, stating he hopes the new study — which was recently published online in the journal Nature Geoscience — offers a little momentum to move in that direction.

Stamenković concluded that there is still so much about habitability on Mars that we do not understand, and it’s long overdue to deploy another mission that addresses the question of subsurface water and possible extant life on the Red Planet, as well as looking for these signals.

If you’re fascinated by the prospect of life on Mars and think humans could one day live in space then join Asgardia today and connect with forward-looking people.