Liquid Water Could Be Just Beneath the Surface on Mars

By Sarah Scoles | April 13, 2015 10:00 am
Gale crater on Mars. Image credit: NASA/JPL/CalTech

Gale crater on Mars. Image credit: NASA/JPL/CalTech

It’s nothing you’d want to baste a turkey with, but researchers have found evidence of supersalty brines on the surface of Mars.

By lowering the melting point of water and actively absorbing vapor, the salts might allow for liquid water to exist on Mars — not billions of years in the past, but right now.

A Salty Solution

Here’s how it works: Mars has water vapor in its atmosphere. At night, that water vapor sublimates (turns from liquid into solid) as ground frost, just like it sometimes does on Earth. But when the frost lands on soils laced with calcium perchlorate, Ca(ClO4)2, it melts. The perchlorate absorbs the water and forms a salty solution.

And just like the salt we sprinkle on winter roads, the martian salt lowers water’s freezing point. Instead of icy dirt, salt may give Mars wet dirt, with the liquid water seeping down into the soil.

Prediction Come True

Last July, a team at the University of Michigan in Ann Arbor predicted that exactly this kind of chemistry might be happening on Mars. Obsessed with what appeared to be liquid droplets on the leg of the Phoenix lander, they holed up in their lab to figure out how that was possible.

In their Mars Atmospheric Chamber, an apparatus that would look at home in a brewery, they simulated Mars’s conditions to see if they could wring water from the air. “When the scientists placed calcium perchlorate or salty soil directly on a 0.1-inch-thick ice layer, drops of liquid water formed within minutes when the chambers reached -100° F,” said a LiveScience article from the time of discovery.

Hypothetical water cycle on Mars. Credit: Martín-Torres and Zorzano

Hypothetical water cycle on Mars. Credit: Martín-Torres and Zorzano

This new discovery builds on that. Researchers found perchlorate in the soil of the Gale crater and calculated that humidity and temperature would be right for brine formation in that same region. The necessary conditions exist at night and just after winter sunrise, the researchers report in Nature Geoscience.

Postcards from Mars

Curiosity has spent almost three years on Mars. In all that time, it’s traveled a whopping 10 kilometers from its landing site. That’s the distance of a weekend warrior’s running race (although no one has to command and control a weekend warrior’s every step from millions of miles away), a short distance that nevertheless has given the rover a taste of different martian environments.

Curiosity has shown us that Mars used to have habitable spots (even if nothing/no one inhabited them) and that billions of years ago, it had an ocean that could have covered the whole planet in 450 feet of water.

And findings like this brine show present-day Mars to be a bit more life-friendly than we thought. On Earth, for example, organisms called halophiles (salt lovers/lickers) would love to live in calcium-perchlorate-land. But, as the authors caution, there’s a lot more to habitability than “just add water.” Mars is dry, cold, and irradiated, and so far shows no evidence that anybody is home. And the dirt where these brine remnants were seen, Gale crater, gets too cold to host any known microbes.

But liquid brines might be abundant across Mars’ surface. So, some further trekking might eventually reveal whether any salty critters still call those soils home.

CATEGORIZED UNDER: Space & Physics, top posts
  • Mike Richardson

    It would require desalination and purification, but at least it’s water. That makes it easier for any would-be colonists who won’t have to worry about bringing water with them. Of course, if there are Martian halophiles, that water might be put off limits to preserve any indigenous biology.

  • noot


  • noot


  • Richard

    Discovering water on Mars isn’t that surprising. I mean during the formation of our solar system, Earth and Mars would probably have looked very similar. They both started as rocky planets, made out of the same materials. The only difference between the two is that Earth happened to have the perfect mass and fall into the perfect range from the sun which allowed it to evolve from the seemingly inhospitable ball of magma that both Earth and Mars started off as and become what it is today. Mars, without the requirements that Earth possessed, became what it is today and maybe the presence of water is just one of the signs of what Mars could have become had it had the right requirements. There could even be life on Mars for all we know, not the kind of martians that we have become accustomed to, but tiny little microbes that could be living deep beneath its surface. Geologist and Biologist Tullis Onstott has been discovering and studying tiny bacteria that is living thousands of feet below the surface. These microbes live in 140 degree Fahrenheit, without the presence oxygen that we rely on to survive. They simply lived off energy that they got from their ability to reduce (transfer electrons to) iron. He developed the idea that these microorganisms got their energy from radiation in the rock. He noticed that wherever he had radiation, he tended to see hydrogen gas forming which is formed when the radiation breaks apart water bonds to create this gas. This gas is the key component that the bacteria need to produce ATP, which is a molecule they use for energy. So to put it in simple terms, these bacteria live solely on radiation, rock and water which we now know all occur on Mars. Could this mean that there is possibly life on Mars? If these kinds of microorganisms are found on Earth that can survive in these harsh conditions that Mars also possesses then why wouldn’t we find a similar kind of thing on Mars? They might not be the kind of life that humans have been searching for on Mars, but still life none the less. 15063896

    • earsz70

      send some of these to Mars in a container (so as not to release them on to Mars itself) with the necessary ingredients and see if they continue to thrive.

  • StanChaz

    What I want to know is this.
    WHY has the American Public has been kept in the dark from the fact that the Mars Rover discovered a half-eaten TWINKIE on the Martian surface?? – surely the TRUE cause of an advanced Martian civilization’s downfall!

  • Zach

    Err… the author may want to double check their definition of sublimation. Sublimation is the phase change that occurs when a solid changes directly to a gas, whereas turning from liquid to solid is simply referred to as freezing.
    Otherwise, very interesting article.

    • tom johnson

      The article stipulates:
      “Mars has water vapor in its atmosphere. At night, that water vapor …”

      So a Gas–>Solid. So ‘Deposition’.

      Then Solid–>Liquid in soil. ie. ‘Melting’.
      When the sun is up, some liquid goes to vapor again via ‘Evaporation’


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