Curiosity is currently on its way up Mount Sharp, in the center of the Gale crater (where it found evidence of water). Illustration: Stocktrek Images, Inc./Alamy

Where there is water, there is life. This is a statement that has been reaffirmed over and over again. Whether it is in the acidic waters surrounding volcanoes or in the dark and frozen wastes of the icy Antarctic, wherever we find liquid water, we find life. That's what makes the most recent find by NASA's Curiosity rover so amazing—Evidence of liquid water on Mars.

In 2002, we discovered that there was ice on the Red Planet. More recently, we found that Mars has more than just a little ice. It has glaciers. Ultimately, this frozen ice contains enough water to cover the entire planet in a meter of water. But liquid water is an entirely different ball game.

The major question that is now being asked is, how can a planet with an average temperature of -55°C (-67°F) have liquid water?

In work that was recently published in the journal Nature Geoscience, the scientists behind the discovery detail their ideas about the Martian water cycle. The team, led by planetary scientist Javier Martín-Torres, who hails from the Luleå University of Technology in Sweden,  asserts that salt is likely responsible for the pockets of water. Much like life is able to subsist in the near-frozen water of the Antarctic because of salt, the scientists state that salt could be present at such quantities that it alters the freezing point of the water, lowering the temperature at which the water freezes so that, in order to solidify, the water has to get a lot colder than it does on Earth.

Previously, we have detected evidence of salts on Mars, and it is this previous evidence that forms the basis of the team's conclusion.

Ultimately, it is believed that the water cycle starts when vapor from the thin Martian atmosphere cools and gets absorbed by salt on the surface of the planet. Then, during the evening, when temperatures go well below zero, the salts become so saturated by water vapor that they form "liquid brines in the uppermost 5 cm [2 inches] of the subsurface". These small liquid pools stick around until the daytime temperatures turn the pools back into vapor. As the day progresses, and things start to cool, the liquid water again appears.

Sadly, Curiosity hasn’t been able to capture any images of liquid water on Mars because, well, the technology hasn't been invented yet. Yes, of course we do have cameras on Mars (as our many pictures attest); however, the cameras don't work in the subzero temperatures where the liquid water exists on the Red Planet.

So on to the main event: Do these pools contain life? Well, we don't know for sure. However, we do know a few things that allow us to make guesstimates. First, since the temperatures are so low, we know that life as we know it cannot exist. Second, since the pools appear to dry during the day, it is unlikely that any life at all could survive. But despite the fact that it is rather unlikely, it is certainly not impossible. And, well, that's something.

What do you think? Is there life on Mars and, if so, will we find it?

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