Future Astronauts Must Deal With Toxic Chemicals In Martian Soil 117
Thorfinn.au sends this quote from Space.com:
"The pervading carpet of perchlorate chemicals found on Mars may boost the chances that microbial life exists on the Red Planet — but perchlorates are also perilous to the health of future crews destined to explore that way-off world. Perchlorates are reactive chemicals first detected in arctic Martian soil by NASA's Phoenix lander that plopped down on Mars over five years ago in May 2008. It is likely both of NASA's Viking Mars landers in 1976 measured signatures of perchlorates, in the form of chlorinated hydrocarbons. Other U.S. Mars robots — the Sojourner, Spirit and Opportunity — detected elemental chlorine. Moreover, orbital measurements taken by the Mars Odyssey spacecraft show that chlorine is globally distributed. [Phoenix principal investigator Peter Smith] said microbes on Earth use perchlorate for an energy source. They actually live off highly oxidized chlorine, and in reducing the chlorine down to chloride, they use the energy in that transaction to power themselves. In fact, when there's too much perchlorate in drinking water, microbes are used to clean it up, he said. Furthermore, seasonal flow features seen on Mars may be caused by high concentrations of the brines of perchlorate, which has a strong attraction to water and can drastically lower its freezing point, Smith told SPACE.com. The high levels of perchlorate found on Mars would be toxic to humans, Smith said."
Re:Anyway (Score:4, Informative)
Can we just pick some bacteria and launch them up there? It's going to happen eventually, anyway. Might as well get it over with.
Rather than just destroying them, why not use them? An astronaut will need a pressure suit to walk around outside anyway since the air pressure is so low. This story got me curious, so I hit wikipedia.
Re:I am surprised (Score:5, Informative)
AIUI, it's not quite that simple.
On Earth, the extremophiles are believed to arisen in more benign environments, and evolved to colonize the extreme environments. It's not clear that Mars ever had the necessary benign environment for long enough for life to arise in the first place, let alone for it to evolve and begin to colonize the extreme margins. (Which, at the time, would have been far less extreme than currently.)
MInor detail, not a problem (Score:4, Informative)
Perchlorate is a reactive and unstable anion that can easily be washed out of regolith, thermally decomposed by baking in an oven, or removed using chemical or microbial treatments. Similar treatments are likely going to be required anyway if you're going to be growing plants in it.
It's also not actually all that toxic. The thyroid absorbs it in place of iodine, reducing the amount of iodine absorbed...it has no other effects, and the iodine uptake interference stops when exposure to perchlorate stops...chronic ingestion is required to make it a problem, an acute exposure will only have a brief effect.
Basically: don't make a habit of eating untreated dirt, and monitor drinking water contaminants. Nothing they shouldn't already be doing. Iodine supplements might be a good idea in case drinking water becomes contaminated and it takes some time to correct.