We’ve known for a long time that there’s water on Mars. Now we know – thanks to NASA’s latest announcement – that some of it is at the surface.
Features called recurring slope lineae – dark lines that appear on Mars seasonally – have been shown to have salts from briny water associated with them. It means that water is in its liquid form and is flowing at the surface of Mars today.
According to NASA, the probable mechanism enabling liquid water to exist is a process called deliquescence, where the salts absorb water from the atmosphere and then release it periodically.
But what does this mean for the prospects for life on Mars? The surface of Mars is a rotten place for life, being exposed to ultraviolet radiation that will kill anything pretty quickly. So it all depends on where the water that life requires comes from.
In this case, the water cycle is all at the surface. So any life would be trying to cling on in a very harsh environment. But another option is that it could be from acquifers, the plumbing system in the rock that feeds these seasonal streams.
If so, there might be regions near the surface where the conditions for life exist, which are protected from radiation. Suddenly the prospects for life gets a lot better. And even though the water on Mars appears to be very salty, we do know of extremophiles that are able to live in incredibly salty environments.
We won’t really know until a Mars probe goes to these lineae to have a look what’s there. The Curiosity rover might even be able to do this.
Curiosity landed in Gale crater three years ago and is currently climbing the 5km mountain in the middle of that crater, called Mount Sharp. That mountain contains a layered rock record of Mars’ history. Every time the rover stops and analyses a rock, we could learn something that revolutionises our understanding of the history of Mars.
Humans on Mars
The larger implications of this week’s announcement may not relate to life. Water is a precious resource. Having access to it at the surface is a game changer when it comes to human exploration.
Astronauts need it to drink. Separate the oxygen and they can breath it too. And oxygen and hydrogen are the components for rocket fuel. Every kilogram of anything you take to Mars costs around A$3 million.
So having drinking water, oxygen and fuel accessible at the surface suddenly means you have much cheaper options for Mars missions. Future missions will carry further instruments and test technologies that will let us answer these questions.
