Future Astronauts Must Deal With Toxic Chemicals In Martian Soil

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."

Comments

Read the signs

[roman_mir]

It's an energy and useful material source:

...perchlorate is used within the pyrotechnics industry, and ammonium perchlorate is also a component of solid rocket fuel....
researchers propose a biochemical approach for the removal of perchlorate from Martian soil that would not only be energetically cheap and environmentally friendly, but could also be used to obtain oxygen both for human consumption and to fuel surface operations.

It lowers water freezing point:

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

and it's a poison for humans:

"It's bad for astronauts because it is toxic for humans, as it interferes with the thyroid," he said.

So read these signs, Mars is even more difficult for human exploration than previously understood, but it provides potential energy source for machines to fuel themselves.

This only means that if we are going to do something in the near future, it's going to be more robots powered by perchlorate chemical reactions.

Re:Read the signs

[Immerman]

>Mars is even more difficult for human exploration than previously understood

I'm not sure that follows. Yes, Mars is a bit more *hazardous* than previously understood, but it also has more readily-accessible resources (power and liquid water). Which wins out would take more than an arm-chair analysis. Especially since the hazard profile is potentially fairly minimal - when outside they'll need to be in protective suits anyway, and when coming inside they'd want to avoid tracking in a lot of dust anyway just for the nuisance factor. In practice this might just provide an incentive to provide better de-dusters in the airlock. I imagine a quick decon shower would do the trick quite thoroughly. So long as the artificial ecosystem includes microbes that digest the local percholate mix any dust that does get in will be neutralized fairly rapidly, just make sure to wash your hands before eating.

The real questions may actually be:
*How does this effect growing soil from Martian sand? Though technically you don't *need* sand to grow soil, it is helpful for a lot of plant types. I suppose in the worst case microbial pre-treatment would be easy enough to do.
*How does this effect concretes made from Martian sand? They're the natural choice for building material since you need only a small amount of the right binding agent to make large structures. Again you could pre-treat the sand, but that's a lot less convenient for construction-scale activities. Ideally we could develop a cement that actually harnesses the perchlorates for an intensely exothermic curing process that produces an extremely strong and/or airtight crystaline structure.

I am surprised

[MyLongNickName]

If there is an energy source in the soil itself, why there isn't an abundant amount of bacteria taking advantage of this. I guess I've come to believe that life will evolve to meet just about any condition, and an energy source seems to be about all it needs. Yet there has been no serious evidence of any type of life currently on mars.

Re:I am surprised

[DerekLyons]

I guess I've come to believe that life will evolve to meet just about any condition, and an energy source seems to be about all it needs.

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.)

Re:Anyway

[fuzzyfuzzyfungus]

Even if you want to introduce microbes, you'll need to find some that are useful under Martian conditions.

They are tough little bastards, so finding microbes that aren't killed will probably be easy enough; but finding ones that are metabolically active(rather than just capable of dormant endurance) could be trickier. Bacteria are pretty good at shriveling up and shrugging off downright alarming conditions(unprotected exposure to the vacuum of space, ionizing radiation, freezing, etc.); but they can't exactly shiver to keep themselves warm.

On the plus side, if you are planning on humans, you'll have to have a climate-controlled habitube setup anyway, so you could presumably use off-the-shelf perchlorate cleaner bacteria in 'scrubber' units that treat contaminated materials before they are introduced into the human support environment.

Re:Safe workplace

[fuzzyfuzzyfungus]

When was the last time an astronaut would survive exposure to anything outside Earth's atmosphere. Keep those helmets on kids, regulations and all that.

I imagine that the problem is astronauts in suits tracking dust back into the airlock and then, once unsuited, breathing in the perchlorate goodness, possibly with a side of delicious silicosis...

I remember reading about a scheme where the 'suit' would remain permanently outside the habitat, with a docking hatch in the rear, specifically to avoid this sort of contamination.

This is good.

[SuricouRaven]

Perchlorate at 1% concentrations?

Perchlorates are very easy to turn into rocket fuel or oxygen. Two things potentially of much use on mars. I expect the processing would need too much bulky equipment, time and manual labor to be practical on a plant-flag-and-leave mission, but a long-term sustainable base could certainly put it to good use.

Don't hold your breath

[PopeRatzo]

Martians will come here before we go to Mars.

I doubt anyone alive today will ever see humans walking around on Mars.

Re:Anyway

[mcgrew]

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.

They have been used for more than fifty years to treat thyroid disorders. They are used extensively within the pyrotechnics industry, and ammonium perchlorate is also a component of solid rocket fuel. Lithium perchlorate, which decomposes exothermically to produce oxygen, is used in oxygen "candles" on spacecraft, submarines, and in other situations where a reliable backup oxygen supply is needed.

Mars, the solid rocket fuel factory

[Taco Cowboy]

Ammonium Perchlorate is a very powerful oxidizer - and has been extensively used to make solid rocket propellant

Since Mars has so much perchlorates around why don't we turn Mars into planet-wide base for building solid rocket fuel ??

MInor detail, not a problem

[cjameshuff]

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.