Could Mars Be A Little Damp?
How To Interpret Science-Speak, If You Must
The search for that necessary pre-condition for life, liquid water, on Mars is one of the holiest grails of modern space science. We’ve learned that water on Mars is easy. It’s the liquid part that’s tough. Mars is just too cold and its atmosphere too thin to allow water to exist in that form for long.
But Mars has a trick up its sleeve. Researchers saw early in the Mars Phoenix Mission photographs blobs of something that grew, then shrank and disappeared. Looked a lot like water droplets. Scientists now think that the trick was done by the addition of large amounts of perchlorates to the water, the very same chemical (found in large amounts there) that would give life a real bad time.
Renno’s team carried out a series of laboratory experiments and found that the lander’s thrusters would have melted the top millimetre of ice in the regolith. The resulting water droplets may have been splashed onto the landers leg. If the concentration of perchlorate was high enough, the water could have remained in a liquid state during the Mars daytime. As time progressed, atmospheric water vapour may have been absorbed, hence the growing and shifting blobs of liquid on the leg. There is also the possibility that the droplets were splashed from pools of perchlorate-rich water already in a liquid state on the surface.
It’s Martian anti-freeze, and that actually improves the chances for life there. Now, whether it improves the odds enough is still an open question, you understand. But liquid water in any form lets flow the chemistry of life-as-we-know-it.
Now you must ask if this liquid water on Mars is a fact, or merely a conjecture. We’ve been fooled before, you know.
However, not everyone is convinced. Fellow Phoenix team member Michael Hecht from NASA’s Jet Propulsion Laboratory in Pasadena, California, thinks that the photographs actually show water ice, not liquid water. The “frost” changed shape as vapour from the air coalesced and froze to the leg. Renno points out that this is unlikely as any ice on the leg would be more likely to sublime, rather than grow, but Hecht believes this could happen if the leg was colder than its surroundings.
So the jury is still officially out. Be sceptical. Hopeful, but sceptical.