Mars is not the dry, arid planet we once thought it was. Under certain circumstances, liquid water has been found. NASA’s announcement has the potential of turning some Red Planet theories on their heads…
Researchers have long wondered whether liquid water might occasionally flow across the surface of Mars today. In 2010, scientists found evidence of dark streaks on Martian slopes. But this was so far sheer speculation. As temperatures on the barren surface of our second closest neighbour in the Solar system are usually well below zero Celsius and the atmospheric pressure is so low, any liquid including H2O will rapidly boil and evaporate.
Nevertheless, the observation over the past 15 years of gullies and surface streaks that appear to change according to the seasons has only heightened the speculation.
The water channels appear in the early Mars summer. They disappear. Then, the water forms again by the autumn.
The latest readings strongly support the theory that those streaks are flowing liquid water. The findings are reported in the journal Nature Geoscience.
Mars Reconnaissance Orbiter and Crism
The Mars Reconnaissance Orbiter (MRO) has an instrument called Crism that can determine the chemical signature of surface materials. It looked at four locations where dark streaks are seen to come and go during Martian summer months. These streaks, called “recurring slope lineae” (RSL), were well known to Mars scientists and were suspected – although not proven – to be associated with trickling water.
Crism has now demonstrated that the RSLs are covered with salts – magnesium perchlorate, chlorate and chloride – that can drop the freezing point of water by 80 degrees and its vaporisation rate by a factor of 10. It is thought that this combination allows briney water to stay stable long enough to trickle down hillsides and crater walls.
It is not yet known where the water from the dark streaks is coming from. The locations of the RSL are mostly equatorial, and any stored water in this region of Mars, perhaps in the form of ice, is thought to exist only at great depths. One distinct possibility is that the salts actually pull the water out of the Martian atmosphere. Another is that local aquifers are breaking up to the surface. However, this does not really fit with streaks appearing at the top of the peaks.
Could this Water support Life?
Mars used to have a giant ocean. But something happened, some catastrophic event… and Mars lost its water in the atmosphere and on its surface. To this day, we still don’t know if life arose on Mars as a result of this past abundance of liquid water.
Any liquid water raises the possibility that microbial life could also be present on Mars. As the study of extremophiles on Earth has shown, life can thrive even in conditions that are hyper-arid, very saline or otherwise ‘extreme’ in comparison to what are habitable conditions for human beings.
On Earth, wherever we find water, we find life.
For future astronauts on Mars, the identification of water supplies near the surface would make it easier for them to “live off the land”. Until now, the trick to producing water for future Mars-tronauts was to figure out how best to extract it from the soil and the atmosphere. This discovery may well decrease the cost, and increase the resilience of human activity on the surface of the Red Planet.
Potential identification of water supplies near the surface would make it easier for humankind to survive and strive on this alien off-world in decades to come…