But, Finding Clues of Life There Gets Harder

The news this week that Mars has water bound up in its soil fulfills at least one of the goals of the Mars Curiosity mission: to find evidence of water. It’s one more checkmark in the “search for evidence of life” column, and it came after one of the first tests to look for water by the roving science lab. Curiosity’s ChemCam shot lasers at samples of soil and sediments it scooped up on the surface of Mars. The laser testing turned up high amounts of hydrogen, which is indicative of water in bound up in the soils.

This is great news because it really clinches the idea that Mars has water. In the past it had lots more, likely flowing across the surface. These days, Mars water is locked inside rocks and sediments, and makes up a frozen subsurface layer similar to permafrost here on Earth. Future Martian explorers who make their homes on Mars should theoretically be able to heat those rocks and distill water out of them to aid in their long-term survival.

The next item on the tickbox of successful Mars exploration will be to find evidence of life. However, another finding released this week proves that it’s tougher to provide that evidence than people thought. That’s because the Martian surface sediments are permeated with the chemical compound perchlorate, and it interferes with the tests that Curiosity does to look for traces of past life.

Perchlorate is a salt made up of chlorine and oxygen. When it’s part of the soil that Curiosity tests, perchlorate causes another chemical reaction that actually destroys carbon—and carbon is part of all living beings that we know about on Earth. If life existed on Mars, then it’s logical to assume it would also contain carbon. And, when an organism dies, it leaves behind carbon traces. So, the presence of perchlorates makes testing for life much trickier. In fact, that presence will likely cause scientists to change their methods and techniques as they search for the chemical remains of past life on Mars.

Mars is turning out to be a very intriguing study target for planetary scientists. It’s a puzzle, but one that we’ll eventually solve, particularly when we send people to the Red Planet to do direct investigations.

Want to know more about these findings?  Read about the water discovery here and the perchlorate work here.