Did Phoenix Burn Martian Life?

May 25, 2009

It sounds like a freshman biology laboratory error: "Too bad Joe, you burned the sample. Anything that was alive is now dead. Very, very dead. Clean up the broken glass and burn marks on the wall."

Down here on Earth, we're allowed to make experimental mistakes. If we damage a sample, we simply collect a new one and modify our technique. Unfortunately, when it's a robot, on the Martian surface that's doing the experiment, there's very little we can do if an experiment goes wrong. In fact, we'd probably have no clue if the experiment had gone wrong in the first place; robots only do what they are programmed to do.

Last year, when the Phoenix Mars Lander was scraping samples of regolith from the surface, it made the bitter-sweet discovery of perchlorate in the soil. Perchlorate can be found in rocket fuel, and as you may have guessed, rocket fuel isn't exactly a healthy addition to anyone's diet.

Although the discovery of perchlorate was a real downer for Mars life hunters (but caused a huge fuss online), there was still some hope. Perchlorate is a salt, and salts, when dissolved in water, can lower the freezing point, keeping it in a fluid state. Therefore, it is well within the realms of reality that there may be pools of salty water (brine) situated in the upper layers of regolith. Amazingly, it is known that some basic forms of life in harsh desert environments on Earth actually use perchlorate as an energy source.

Awesome! The search for Mars life is still on!

Not so fast. Everything from the Viking Mars landers in the 1970's to the Phoenix Mars lander last year have turned up blanks for the search for ET in the Martian dirt. Not only that, but there have been no discoveries of organic compounds. Organic compounds should have been discovered by now; cometary material is known to contain organic chemicals and we know that Mars has been peppered with this material in the past. So where are all the organics?

In an attempt to detect organic compounds and basic life forms, our robotic landers use small ovens to heat samples up and then analyze the gases given off. But therein lies the problem, there's a reason why perchlorate is used in rocket fuel. It burns.

Usually at low temperatures, perchlorate is harmless, but when heated to a few hundred degrees, it releases large quantities of oxygen. Oxygen fuels fire, burning any combustible material. Organics are combustible! It's therefore little wonder we haven't found and organic chemicals (or life) on Mars - each scoop of soil our 'bots collected got charbroiled! Rather than hunting for life, Phoenix was sanitizing the samples.

Oops.

Now scientists are trying to think up other ways to analyze Martian soil for organics. I'm thinking we might have to wait for the first manned missions to Mars before we can conclusively work out whether Mars has the potential to support life. Human ingenuity will beat a programmed robot every time...

Source: New Scientist

Comments

[Charles Kuester]

Talk about unintended consequences.

[Charlie (Colorado)]

Well, strictly perchlorate doesn't burn ... it's an oxidizer. Makes other things burn like a sonuvagun, though.