Molecular Monday: Perchlorate Salts on Mars

Today’s post is part of a bi-weekly series here on Planet Pailly called Molecular Mondays, where we take a closer look at the atoms and molecules that make up our physical universe.

It’s hard to imagine how anything could survive long on Mars. This has been especially true ever since 2008, when the Phoenix Lander conducted the first ever wet chemistry experiment on Martian regolith and detected a chemical called calcium perchlorate.

I haven’t looked into how this wet chemistry experiment worked, but I’m guessing it involved mixing water with a sample of Mars dust and then running a spectroscopic analysis.

Of course when this calcium perchlorate was detected, the first question was: did Phoenix contaminate its own sample? On Earth, perchlorates are an increasingly common pollutant produced by (among other things) rocket fuel. But if there was any serious contamination of the Phoenix landing site due to Phoenix’s landing rockets, we’d expect to find ammonium perchlorate, not calcium perchlorate.

Also subsequent experiments and observations by the Spirit and Opportunity rovers, the Mars Odyssey orbiter, and other Mars missions have found that chlorine is scattered all over the planet. Most of that chlorine is likely bound up in perchlorate form, and it’s now estimated that calcium perchlorate, magnesium perchlorate, and other perchlorate salts make up anywhere between 0.5% and 1% of the Martian regolith.

For humans, that’s an alarmingly high percentage. More than enough to kill you, or at least to cause you serious thyroid problems. But if you’ve been following along with my blog, you know I’ve been living on the surface of Mars and growing my own food here for over a month now. So why am I not dead?

Well… it turns out there is life here on Mars, and the natives have been surprisingly helpful. More about that in my next post.



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