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If you’ve read much about the Martian environment and human missions to the planet, the subject of perchlorates will have come up. Ingesting even tiny amounts of perchlorate salts can lead to severe sickness and death. However, they contain a useful amount of oxygen.
If this has all been covered elsewhere, I apologise, but I did search first.
What is Perchlorate?
Perchlorate is an ion, one chlorine atom bonded to four oxygen atoms and carrying a single negative charge. So it’s written as ClO4-¬¬
It usually occurs bonded to a metal atom such as Magnesium. Also, it’s important to remember that perchlorates can dissociate (disintegrate) into a range of other oxychlorines, for example when subjected to ultra-violet light, and some of which appear to be even more dangerous to human health.
Ammonium perchlorate has been used as a rocket oxidiser. In fact NASA’s SLS solid rocket boosters use it with aluminium powder as the fuel.
Void and others discussed processing perchlorates here, and much of the chemistry involved needs time to read. The gist was ‘there are useful chemicals locked up in the Martian dirt which we can process into a range of resource materials’. Bacteria were mentioned as there are species which can digest components of the dirt and will yield minerals and gases we can use.
But since I couldn’t find a thread devoted to perchlorates in general, here is what I’ve dug up. Here's an overview of the deadly dangers and huge potential of perchlorates.
What’s the Problem With Perchlorates?
The basic problem is that they can interfere with the function of iodide uptake in the thyroid gland which leads to hormonal problems. That may sound humourous to a teenager, but long-term this can mean goitre, low metabolism rates and slowing of major organs. It messes with the normal development of an unborn baby and the development of a young child.
The maximum safe dosage of perchlorates is very small - 0.7ug per kg of body weight per day. And beware of eating plants that have taken perchlorate ions from the soil! Martian farmers may have to rethink their master plan if it involved using raw Martian dirt.
The iodide uptake problem is reversible, however, once perchlorates are taken away.
Think of plans to pump and compress local atmosphere for ISRU applications, including life support. Think of marstronauts coming in from Marswalks covered in dust, which gets into the air, which they breathe in. If there’s no effective plan to deal with this, living on Mars may simply not be possible for more than a few days or weeks without confining all human life into a hermetically sealed tin can.
Is There No Hope?
Yes! There is hope for human life on Mars! Here are several angles of attack:
Dust elimination
Bacteria to the rescue
Grabbing the oxygen
1. Dust Elimination
Filtering The Dust
The mining industry already knows a great deal about filtering fine dust particles. For example, the air sucked into gas turbines needs to be very pure to prevent wear and tear over time, so they have developed high-efficiency particulate air filters (EPA) which can capture 99.95% of 0.3-micron particles. From EngineerLive
What size are the dust particles on Mars? According to this study, most are around 1 micron, and in dust storms larger particles are picked up and flung around too. So I would guess (not being a mining engineer) that habitats and ISRU units sucking in the air would have these types of filters but would slowly accumulate perchlorates.
Airlock Systems
Mines use a great deal of water to keep the dust down. But for a water spray or mist to be effective, water droplet size needs to be quite close to the dust particle size.
Perhaps a combination of a water screen then a blast of air passing through filters would cut down most of the toxic dust.
A lot of Martian dust may carry a static charge. An electrostatic system that pulls charged dust particles off your suit may have some effect, although using too high a field strength could mess with the electronics in a suit and the airlock itself.
Pharmaceuticals?
Might there be a way to develop a pharmaceutical that blocks the effects of perchlorates on the uptake of iodide in the thyroid? I have no idea, but you can count on someone looking into it at some point if all these other methods don’t eliminate the problem altogether.
2. Bacteria to the Rescue!
More than 50 species of bacteria have been discovered which actually eat perchlorates for breakfast and burp up oxygen. In this paper from researchers at Cambridge University the whole question is tackled convincingly.
The biogeochemical redox cycle of chlorine is well understood…. And consists of three key steps: (1) ClO4¬¬-¬ reduction; (2) chlorite dismutation and (3) oxygen reduction.
As a side-note, I discovered that dismutation is a chemical reaction simultaneously involving oxidation and reduction. I never knew that was possible!
Rather than having to extract the reaction products from inside the bacteria’s cell, it’s possible to extract the enzyme it uses in the reaction and use that instead. This leads the researchers in the above paper to propose and develop a portable oxygen generator (for use in emergencies) that uses this enzyme. One hour of breathable oxygen would need 100g of the enzyme and about 6kg of perchlorate-bearing dirt, then some water. If it was a practical system I can imagine it being built into all rovers and bases and even perhaps suits as standard issue.
To develop this a little further, I can imagine a microbiology lab on Mars being sorely tempted to develop a strain of these bacteria that can survive under subsurface conditions, away from the worst of the GCRs and solar radiation. An extremophile that eats up dangerous perchlorates and gives off oxygen? What could be better? Could it spread around the planet and pump up the atmospheric pressure, while rendering the dirt a little safer to humankind? It wouldn’t be 100% effective, surely, and the main effect might be that the lab gets closed down by the outrage amongst other settlers who still want to search for indigenous lifeforms. This begs the question of who is going to propose a set of regulations tp govern planetary protection and terraforing initiatives? Now is the time to start.
3. Grabbing the Oxygen
From the sources I’ve cited so far it sounds like it would not be hard to harvest the oxygen from the perchlorate-eating bacteria. However, it’s late and I’ve typed enough for one day!
Last edited by JohnX (2022-07-23 20:03:57)
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For JohnX re new topic....
It appears there was only one topic with the word "perchlorate" ...
Index» Life support systems» Perchlorate for Chemosynthesis on Mars by Void.
There are numerous topics with posts that contain the word, as your search would have shown.
Your new topic seems (to me at least) to share the stage with Void's topic, and to add a wide overview upon which our members can build, if they are so inclined.
(th)
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That's right. I was just about to add an edit to that effect - not much new here, and Void's thread may have covered some of this already. But this takes the subject mainly from a life support angle rather than the chemical engineering & resource extraction angle.
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For JohnX re #3 and development of new topic
The member most likely to be both able to join you in meaningful development of this topic, and potentially interested in helping is RobertDyck.
This forum has received many contributions over more than 20 years, and some of them would be useful for an individual or a team planning to set up shop on Mars.
If you are so inclined, your new topic might be developed as a field guide for such settlers.
Please consider making future contributions in chunks that are tightly focused and easily found.
Here-to-fore, forum members have contributed without much concern for long term accessibility of their work.
You and Scott Beach, and Mars_B4_Moon, are all members of the long-ago crowd who built the forum archive.
While SpaceNut and RobertDyck have been here from the early days, the three of you took some time off for other interests and activities. it is good to have all three of you back.
However, this forum is changing as new members join, and there ** seems ** to me to be a shift in focus from speculation to action, or at least laying the ground work for action.
It seems to me that your new topic provides an opportunity for future Mars settlers to gain a more realistic understanding of the environment than might be found in the brain of the average Earth dweller.
Best wishes for success!
Plus! If you would like for SpaceNut to contact other forum members from an earlier time, we are working on an automated outreach campaign. A precursor is simple manual testing of procedures. Please feel free to suggest names of folks you think might be interested in rejoining the forum and (most importantly) contributing to development of your new topic.
(th)
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I have taken care to read the posts. I will try to use better than normal quality here, as this seems important.
If the members wish to suggest the modification or deletion of materials I post, I will cooperate for that.
Other members here have suggested coveralls to be worn over a suit, and presumably those stay outside, probably in a shed of some kind.
I will draw from working in a mining process and also working at a research center, as various things like electronics, electrical, Instrumentation, Metrology, programming, and many other things.
"The solution to Pollution is Dilution". As you know, I have been interested in water impoundments for Mars. I have also suggested what I call Barometric airlocks. JohnX has mentioned sprays to help remove the toxins. I am now thinking "Car Wash". Some modifications of that might help. Motorized brushes with water flushing into a drain that goes into a pond. Possible travel through the pond to help clean, and to adjust pressurization from the low pressure of Mars to habitat. Don't forget the car wash soap. Biodegradable?
This particular pond will then get polluted though with toxins. I suggest "Flocculants" be added to the water to promote the sinking of the materials to the bottom.
https://www.watertechnologies.com/lp-ww … water_usa_
https://en.wikipedia.org/wiki/Flocculation
In the mining operation in order to reuse water a large disk-shaped pond would take a slurry of fine tailings and water. Flocculants would be added to it, and a "Rake" would scrape the bottom. The flocculant made the rock dust sink to the bottom. The rake would stir the somewhat dewatered muck on the bottom towards and outlet, and then that output would go to a "Tailings" pond. The bulk of the water would then be brought back into the facility for reuse.
I suppose that a modification of this could be tried. Probably on a smaller scale. And I wonder if bacteria could partially treat the dust that would settle to the bottom of the tank. Then also some process to remove the muck might be warranted.
And then although it was not my work to do chemistry, at that research center, we were trained to some extent how to deal with glassware that had had chemicals in it.
It might involve washing 3 times, in some cases only with water, and in other cases 1 wash with a solvent and 2 washes with water.
So, if you did 3 washes, then there would be 3 stations in serial fashion, probably the first just to get the bulk off, and the next two getting fussier.
And then of course you would not bring the suit parts into your living quarters, but a special changing room, I presume.
Needing lots of water, I presume that for this you would want some huge amounts available and a way to initially clean water from ground ice.
With so much trouble for outside activities, I would think planning should avoid those, and robots could be used when possible.
Also, robots might be able to clean an outside area where it might be necessary for a human to work. Not sure how that could be done.
Having equipment in tents or sheds might make sense, the interiors of those being kept somewhat cleaner than the outside.
As far as children and babies, I would think that until methods are completely tested on adults, there would be no children or babies on the surface of Mars. Maybe in orbit.
Done.
Last edited by Void (2022-07-24 09:17:36)
Done.
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For Void ... your substantial contribution to this new topic of JohnX give me encouragement to think the topic might amount to something.
All the topics in the forum amount to ** something ** This is not intended as a criticism, but instead, as observation that some topics have greater long term value than others. Your topics have produced some stunning ideas, which I expect to show up down the line as complete industries. The ballistic delivery of selected hard goods to Mars is the lead example but there are others.
I'm hoping this post will draw your attention to an opportunity inspired by your mention (again) of the aqueous portal for Mars residents. I have long thought this to be an attractive idea, and am hoping you might be willing to deliver a post into this new topic, showing your idea with your terrific images, and with the numbers that rarely accompany images.
Because numbers are not your strong suit, I'm hoping you will enlist other members to help you.
What I'd like to see is a post that contains ** all ** the elements that might show up in a Wikipedia article on "Void's Aqueous Portal for Mars"
It might take several tries to arrive at the result I am looking for, but if you are game, then I am hoping JohnX will be supportive.
JohnX .... this is a topic you created, and you are therefore both the creator and manager of the topic.
You can request Admin support to keep the topic flowing in whatever direction you would prefer.
Most existing NewMars members are respectful of the desires of the topic creator, but occasionally an author will be so inspired they will create a post that veers wildly off topic.
This topic is so narrowly focused it should be (relatively) easy to keep it on track.
(th)
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What would we use for dilution since fresh water is another of those energy equations for mars let along free hydrogen?
The enzyme as a biological catalyst that is usually a protein is interesting and I wonder what particular chain of proteins are required.
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Yes, well 1/3 of Mars is apparently covered with 300 feet / 90 Meters of water ice.
So, water.
1) Take off your coveralls, maybe hang them on a device that can shake them out after you are gone. Probably in a tent or shed.
2) You go to the next chamber in the shed, and use compressed air and brushes to sweep dust off of your suit and to the 1st chamber.
3) You might enter a Barometric airlock situation where you are immersed in water. Again brushes, and perhaps a stream of water.
* I specified 3 stages of liquid on a guess, but maybe just one.
4) You emerge into a partially pressurized air chamber and take a shower. The water runs down into the tank. You might have brushes again while in the shower.
5) You go to a further pressurized chamber with proper breathable Oxygen.
6) You take off your Space Suit and hang it up.
7) You leave the changing room and wash hands and feet, maybe even a shower again, but this time your body.
8) Get dressed and join the habitat community.
Done.
The tank where the dust washed into receives some flocculent chemicals to make the dust clump and settle to the bottom of the tank.
Periodically a robot hoovers up that material on the bottom of the tank, and it is disposed of outside somewhere.
As for the room in the shed, where the coveralls were hung up. The robots shake that dust out and sweep the surfaces to reduce the residual of dust.
Done.
No Children until a method that works is proven and reliable.
Done.
Last edited by Void (2022-07-24 21:00:17)
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I see I was only handling the dust. It is good that the Perchlorates would dissolve in water, so dilution will be important.
Also though, bacteria that can feed on those dissolved salts would be valuable, otherwise the water would have to be continuously distilled.
It may be that multiple wash stages would be needed, but I would hope to minimize the number of stages of cleaning.
Done.
Done.
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Dust will be a hazard but I did find some discussion on perchlorates about 6 months ago, if I have time I might link to some older topic discussions. One idea in the older threads was getting an MSR mission moving bring it back home to see exactly what is in the dust and rocks, check conjectured existance as a mixture of Ca ClO4 Mg NH4ClO4, the ideas to deal with the issue the same as here, simply was adding water to make perchlorates break down, and one byproducts is oxygen.
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I would suggest washing any visible dust off of space suits prior to entry into the hab. Soil can be manufactured by seiving regolith of coarse particles, washing the perchlorate out of the fines and then adding organic matter.
The perchlorate ion is quite unstable. I read an article a couple of months back that suggested that a solution of perchlorate ions could be broken down into oxygen and stable chlorides, by passing a weak electric current through the solution.
Last edited by Calliban (2022-07-26 07:18:18)
"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."
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JohnX .... this is a topic you created, and you are therefore both the creator and manager of the topic.
You can request Admin support to keep the topic flowing in whatever direction you would prefer.
Most existing NewMars members are respectful of the desires of the topic creator, but occasionally an author will be so inspired they will create a post that veers wildly off topic.
This topic is so narrowly focused it should be (relatively) easy to keep it on track.
(th)
Thanks for your valuable input tahanson. I will devote some time in the next few days to developing the theme.
Void, I'm glad you are contributing ideas to this. You have some great ideas for a fully-developed base. I'm wondering how a starter base would cope with perchlorates, also. Did you see NASA's idea for a Mars suit which attaches to a port on the outside of the base and the astronaut crawls into it, seals it up & detaches from the base? That way perhaps, the outside dust won't get inside so easily. But there's no stopping those micron-sized particles from finding a way in eventually. Their concept is called Suitport
Photo of development unit here
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You have a nice topic JohnX.
Callibans notions of electric current flow are of interest.
For initial missions, could it be possible to spray something on the suits that would neutralize the Perchlorates. A chemical reaction? Removal first if possible and then neutralizing agent. Something like a safe biological material. Maybe also including the enzymes that are predicted to allow the extraction of Oxygen from Perchlorates?
Not sure what that could be.
Done.
Last edited by Void (2022-07-26 10:02:13)
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https://newmars.com/forums/viewtopic.php?id=8478
Perchlorate for Chemosynthesis on Mars
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You have a nice topic JohnX.
Callibans notions of electric current flow are of interest.
For initial missions, could it be possible to spray something on the suits that would neutralize the Perchlorates. A chemical reaction? Removal first if possible and then neutralizing agent. Something like a safe biological material. Maybe also including the enzymes that are predicted to allow the extraction of Oxygen from Perchlorates?
Not sure what that could be.
Done.
A suit spray - sounds possible - you mean like a shower in the airlock? For a first mission in a Starship-sized craft that might be feasible if they can keep the mass of liquid down or bring a mini-spray production unit, just add water and other ingredients.
For the enzymes, I don't know how long the reaction would need in order to be effective.
Then recycle the spray liquid, filter out the dissolved dust. This would need some equipment, piping etc. Maybe most of the parts could be 3D printed after arrival.
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I would suggest washing any visible dust off of space suits prior to entry into the hab. Soil can be manufactured by seiving regolith of coarse particles, washing the perchlorate out of the fines and then adding organic matter.
The perchlorate ion is quite unstable. I read an article a couple of months back that suggested that a solution of perchlorate ions could be broken down into oxygen and stable chlorides, by passing a weak electric current through the solution.
I found this article (abstract only):
The results of a study of the effect of the front edge duration of a voltage pulse (τ) on the electric breakdown of ammonium perchlorate single crystals are submitted. Experiments have shown that at τ<1.5 µs, the breakdown threshold field increases with reduction in τ and does not depend on τ at τ>1.5 µs. It is shown that the electric breakdown of ammonium perchlorate results from an impact generation of electrons. The impact generation rate of electrons versus electric field and the diameter of the through channel being formed during electric breakdown in ammonium perchlorate are estimated.
article here
So that's ammonium perchlorate which is I believe what's been used in SRBs as oxidiser. Perhaps you found a different article. I didn't learn too much from this abstract!
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Lightning May Create Martian Perchlorates and Carbonates
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