Designing GMOs for human Mars colonies: Follow the 'toxic salt'

How do you colonize a planet that's saturated with toxic salt? The more that we learn about Mars, the more we realize that toxic salt will be an issue and that part of the solution might be to remove it.

Before using the Martian dirt to grow staple grains such as wheat and corn, and especially water-loving vegetables and fruits, we can implement various filtering procedures to remove an ion that's ubiquitous on Mars and forms salts that we don't want to ingest. The ion is calledperchlorate (ClO4-) and it's not desirable to have on the menu, because it interferes with thyroid function, so filtering makes sense.

But filtering alone would be a waste, because perchlorate is also potentially useful on Mars for the same reasons that it's used on Earth: It contains energy and oxygen and lots of it. For that reason, it has been the major component of solid rocket fuel for decades, and today we know that the oxygen and energy in perchlorate also can be utilized by certain microorganisms. Taking those organisms and modifying them genetically for survival on Mars, or doing the reverse—copying genes from perchlorate-loving organisms and giving them to organisms that are suited for the Martian environment for other reasons—humans could create new microbes that could remove the perchlorate and synthesize useful products from it. Some engineered microbes, for instance, could help process the perchlorate into rocket fuel. Others microbes could extract molecular oxygen—Othe kind of oxygen that we need to breathe. The current atmosphere on Mars is mostly carbon dioxide (CO2) with exquisitely low air pressure, but the modified organisms could release perchlorate-derrived O2 into the atmosphere to help with terraforming—modifying the planet to be more like Earth.

Discovery of perchlorate on Mars: Strange and eventful history

For now, air pressure at the Martian surface is so low that it can barely keep water in a liquid state—unless the water is loaded with salt, which changes water's properties dramatically. With a salinity of 33.7 percent, the Dead Sea is so salty that you can float. That's insipid compared with Don Juan Pond in Antarctica where the salinity of 44 percent, but Mars water is even saltier and the reason is perchlorate. Several years ago, images from NASA's Mars Reconnaissance Orbiter (MRO) revealed streak marks suggesting water running recently on the surface, plus data from Mars rovers and from meteorites known to have originated on Mars suggest that regions of the Martian crust have been underwater in the distant past.

Equally as helpful in the search for Martian water, a NASA probe called Phoenix landed on Mars in 2008 and soon detected perchlorate in Martian dirt everywhere it looked. Then last September, the MRO, still working diligently from orbit, detected perchlorate in those streaks that seem to have been carved by water, and everything fit together. Water erupts periodically from under the Martian surface and it remains liquid because it's full of perchlorate salts at concentrations much higher than the salts of Don Juan Pond.

Along with clinching the case for water on Mars, the finding of perchlorate on Mars put a twist on a story that began 40 years ago, when NASA delivered two probes to the Martian surface in the summer of 1976. They were called Viking Lander 1 (VL1) and Viking Lander 2 (VL2) and each had a chemistry instrument package called a gas chromatograph-mass spectrometer (GCMS) whose measurements seemed to indicate a lack of organic matter samples of the Martian dirt. That was surprising, because, regardless of whether Martian microorganisms were present at the two landing sites, organic matter was expected simply because it was known that Mars was pounded constantly by meteoroids carrying organic matter from space. But the VL1 and VL2 probes actually two organic compounds: chloromethane and dichloromethane. The Viking chemistry team dismissed these two compounds to be contaminants from Earth, because they were cleaning agents like the ones that had been used to clean the probes before for launching them to Mars. After all, why would it have just those two organic compounds on Mars and no others.

But now we know the answer. You actually would have those two compounds on Mars because of the perchlorate. Add perchlorate to a mix of your typical organic compounds like those present in microorganisms or those carried on meteoroids and it produces chloromethane and dichloromethane —exactly what the Viking GCMS devices found.

That solved a 40 year-old mystery, but in an age when we're considering sending astronauts and later colonists to Mars it also gives us a problem, namely that the Martian environment is toxic, at least to us humans.

Health issues of perchlorate on Earth

Perchlorate occurs naturally on Earth and is also produced industrially due to its usefulness in solid rocket fuel. Just as you might be reluctant to purchase model rocket engines that have passed their expiration date, the military and rocket industry avoids using solid fuel in missiles and boosters. Fortunately, most missiles carrying weapons wait around without being used, so after a certain time the solid fuel is replaced. This has led to cases of industry being accused of inappropriate disposal, leading to perchlorate contamination of water supplies. IN 1988, Pacific Engineering and Production Company of Nevada (PEPCON), which produced solid fuel for the solid rocket boosters of NASA space shuttles, had a terrible accident at its Henderson Nevada plant. The Environmental Working Group (EWG) grew increasingly concerned over the years and when EWG heard about a research group in Texas that had developed very sensitive and specific tests for perchlorate, they sent lettuce samples from five states (Arizona, California, Florida, New Jersey, and Texas), some samples from conventional farms, some from organic farms.

The main reason why perchlorate is a health concern is that the ClO4- molecule is mistaken for iodide ion by cell transporters that normally deliver iodide into thyroid cells. This can lead to hypothyroidism (under-active thyroid), a problem that's exacerbated by perchlorate because it is favored over iodide in excretion to a mother's breast milk and uptake from the milk to the infant's thyroid, placing infants particularly at risk for hypothyroidism even when perchlorate levels ingested by a mother are fairly low. There is also a possible connection between perchlorate and thyroid cancer, but it was really the hypothyroidism issue that led to EWG investigation.

Lettuce was chosen for analysis because it consumes a lot of water during its growth, so EWG saw it as a possible canary in the coal mine. In 2004, the samples were indeed found to contain perchlorate, and interestingly perchlorate concentration was two orders of magnitude higher in samples from organic farms compared with conventional lettuce samples. The reason has never been resolved, but subsequent studies have suggested that perchlorate levels are not high enough to be a health issue anywhere in the US. Moreover, exposure to nitrite and other agents would overshadow any perchlorate issue in terms of of effects on the thyroid.

Interesting—and providing a connection between perchlorate on Earth and on Mars-- is that one source of nitrate fertilizer that was used on both organic and conventional farms in the 20th century was from the Atacama desert in Chile. Naturally occurring perchlorate is particularly abundant in the Atacama. This is one reason why planetary scientists and astrobiologists have been using the Atacama as a Mars analogue environment, a place similar to Mars and thus where equipment destined for the Red Planet can be tested.

Living with the perchlorate on Mars

Unlike the Earth situation, controversy does not surround the question of whether the highly concentrated perchlorate in the Mars dirt would be a health issue for humans. It certain would be, and that's one reason why biotechnology will be key to Martian colonies. When we talk about using genetic modification to survive in the Mars environment with its high concentrations of perchlorate, it doesn't mean editing the genomes of future human Mars colonists so that perchloride will not be toxic. Whatever enhancements might be considered for settlers, whether involving gene therapy or implants, they'll still need thyroids and nothing that we can do will change the chemistry of perchlorate and iodide ions. That means we'll have to remove perchlorate from water, or anything else that humans ingest. But when it comes to microorganisms, we can be a lot more creative, as we've already been in biomedicine and agriculture.

Perchlorate salts are abundant deep in Earth's oceans, where they spew out from hydrothermal vents. Certain species of Archaea and Bacteria flourish around the vents, not only tolerating perchlorate but making good use of it. Molecular oxygen (O2) from the atmosphere is absent at such depths, but these microorganisms—let's call them perchlorophiles—utilize the four oxygen atoms from each perchlorate just as aerobic organisms use O2 for drawing energy from food molecules. Though physically closer to us than Mars is, the deep ocean is a very alien environment. It's challenging to reach with instruments the conditions are hostile to humans, so the the perchlorate-thriving Archaea and Bacteria are fairly new to biology. In contrast to well-known microbes like E. coli, we're not accustomed to using them in genetic engineering projects. But once  the biochemistry and molecular biology of these exotic microbes is understood better, their genes could help open a new biological frontier to go along with the Martian frontier that now beckons to become humanity's second home.

David Warmflash is an astrobiologist, physician and science writer. Follow @CosmicEvolution to read what he is saying on Twitter.

  • lab seven

    The lack of sufficient gravity will kill off any long term colony.
    So why make believe we will soon inhabit this cold desolate waste of a planet? Find a better goal in life. Big rotating space stations are the real future of man in space. Asteroid mining makes sense. Even more sense mining helium 3 from the Moon. But Mars talk is senseless. Mars is NOT your stepping stone to the stars.

    • Grafton Is Dust

      So lack of gravity will kill off any Martian endeavour, but space stations are infallible?

      Mars is the best testbed we could get for practicing terraforming. It has H2O that can be mined, it has minerals to be used.

      Comparatively, the moon would require a constant supply of materiel from Earth, whereas Mars actually has the possibility of self-sufficiency. Space Stations wouldn’t be self-sufficient either.

      Not to mention that you’re assuming this is a Zero-Sum game. We can and are approaching all possibilities.

      • lab seven

        [1] Moon has water! Where were you in 2009 when NASA executed it’s lunar-water finding mission called Lunar Crater Observation and Sensing Satellite, or LCROSS?
        [2] Helium 3 makes the Moon economically viable. Most likely will be mined by robots.
        [3] You said “Space Stations wouldn’t be self-sufficient either.” Yes all supplies could be brought robotically from the asteroid belt. There are water based asteroids out there, not to mention an incredible mining resources.
        “Practicing terraforming”; for what ? Do you have any idea what it takes to travel to the Alpha Centauri star system at 25 trillion miles ? We can’t as a planet produce enough chemical fuel to make it. Stable antimatter drive may take over 100 years to make safe for fuel.
        Do you have any type of science degree from an accredited University ?

        Is this a product of STEM ? QUOTE: “Not to mention that you’re assuming this is a Zero-Sum game. We can and are approaching all possibilities.”
        I hope I’m not paying taxes for that. If so the weak minded high school teachers are teaching lust and fantasy rather than rational science and research. Nothing better than good old smart hard work and read, write, and arithmetic .

        • Grafton Is Dust

          1) I wasn’t aware of LCROSS, so the findings are welcome. That said, it merely confirmed that water exists on the Moon, it didn’t confirm whether it was in suitable quantities, at least not according to any of the papers linked by NASA on the subject,
          2) Helium-3 is only useful if we actually developed a reactor capable of utilising it. We haven’t even managed Deuterium-Tritium fusion with a net positive power output, nevermind Helium-3, a substance with even less research put into it,
          3) There are water-based asteroids, but given that the asteroid belt is the greatest concentration of them, and lies beyond Mars’ orbit, it seems like a less-viable alternative than simply colonising Mars,

          Everything in this discussion is hypothetical, so no, of course I don’t have a plan to travel to Alpha Centauri, otherwise I’d have submitted it to NASA or the ESA and received my Nobel Prize as we wave bon voyage to the departing ships. We don’t even have a real plan for getting people to Mars yet.

          I don’t understand why you’re asking for my education details. If I did tell you I had them, you’d say I was lying. If I said I didn’t have one, you’d utilise it as an ad hominem to negate my opinion on the matter.

          Plus it does leave the question open of, “what are you doing then?” Y’know, other than griping at internet articles. What are you actually doing to further progress, research and rational science?

          Also you’re a very silly person if you don’t understand the necessity of imagination in the pursuit of progress. Everything we enjoy now was once a fantasy. We’ve already surpassed a lot of the works of Jules Verne, HG Wells and others. Today’s sci-fi is tomorrow’s reality, even if tomorrow takes a while to come around.

          Why are you liking your own posts, by the way? I mean, if you want that kind of self-gratification, there’s easier ways to do it on the internet, mon ami.

          • lab seven

            You have no idea of what your talking about.
            For instance, Your statement: “We haven’t even managed Deuterium-Tritium fusion”. The level of dumb in what you just said is really far gone.
            Funny in the way you state your misinformation in an attempt to make yourself sound scholarly.
            Yes, I would not believe an accredited institution would have granted you a science degree of any type.
            Why don’t you wiki Helium-3 ?
            The whole point is you can make a viable reactor with helium 3. It’s akin to cold fusion.
            It’s just Helium 3 is rare on the earth and super abundant on the moon.

            Why don’t you study real facts in real science before you comment?

            That’s what I figured. A sci-fi buff (Jules Verne, HG Wells). Don’t forget Capt. James T. Kirk and Mr. Spock.

          • Grafton Is Dust

            Ah, cold fusion, and I’m the one living in a fantasy world?

            You also quoted me out of context there, I said: “We haven’t even managed Deuterium-Tritium fusion with a net positive power output.” But you either knew that and disregarded it, or decided to misquote to try and undermine my point?

            If it’s a material that’s only available in a remote location, then it isn’t going to be fantastically commercially-viable, especially with the cost of transporting material to and from the moon.

            But go on, continue with ad hominem insults and cherry-picked quotes, it’s an amusing diversion. :)

    • Rob H.

      What are you going to do in your big rotating space station? Write sonnets?

  • Debbie

    There will be no Martian colony in the foreseeable future. Since we put men on the moon, the main purpose of our government has devolved into paying lots of people to do nothing or to do something badly. A project to colonize Mars would require paying lots of people to do lots of things well.

    Space exploration isn’t even among the top two NASA priorities anymore. According to NASA administrator Charles Bowden, its first priority is to help Muslims feel good about themselves. Going by NASA’s budget, monitoring, modeling and predicting weather patterns and changes in weather patterns on Earth also takes priority over space exploration.

    • Grafton Is Dust

      Gunna need a citation on that Muslim claim, Debbie, sounds like you’re trying to being politics into a scientific discussion.

      NASA’s mandate remains in space exploration, but this is a matter of space _colonisation._ Hence why they’re aiming to assist data-gathering for missions to put people on Mars, but have no direct plans to do it themselves.

      • Debbie

        Here’s NASA administrator Charles Boden saying it:

        Politics are inseparable from a manned Mars expedition, because it’s not something that could happen without political will.

        Manned space exploration is still part of NASA’s mandate, but when its chief administrator states that his foremost priority is to make Muslims feel good about themselves, and the study of Earth weather and weather patterns gets higher budgetary priority, it can no longer be claimed to be its top priority.

        The FY 2017 budget provides $5,601 million to the Science Mission Directorate. The budget request:

        • Includes five major science areas – $2,032 million for Earth Science to improve climate modeling, weather prediction, and natural hazard mitigation, through Earth observation from space. The budget supports launch of Landsat 9 as early as 2021, and Landsat 10 in approximately 2029. The request also includes funding to increase the capabilities and uses of multi-spacecraft constellations of small scientific satellites.
        – $1,519 million for Planetary Science to explore the planetary bodies of our solar system. Included is funding for a mission to Jupiter’s moon Europa, for continued operations of the Mars Opportunity, Mars Odyssey, and Mars

        Data about Earth’s weather and weather patterns won’t be much use for a Mars colony.

        • Grafton Is Dust

          Good thing NASA are letting private enterprise take over the burden of it then. They’re planning on using the first Red Dragon launch to gather data, in exchange for assisting SpaceX with their own data, for example.

          Plus that quote is from 2010, and so somewhat out-of-date. That convenient soundbite cut out the context afterwards, in which he stated:
          “It is a matter of trying to reach out and get the best of all worlds, if you will, and there is much to be gained by drawing in the contributions that are possible from the Muslim [nations].”

          I don’t see any problem with organising international collaboration, and given that the US already collaborates thoroughly with the ESA, as well as working with the Russians and Chinese to a lesser-degree, plus assisting with the Indian space program, it makes sense to engage nations in the Middle East to utilise their scientific capabilities to add more to the workforce and make it more international.

          • Debbie

            Private enterprise built our moon rockets and moon landers too. They didn’t do it for free. Private enterprise won’t colonize Mars without substantial taxpayer subsidies, regardless of what they’re saying about it now, and that will be the sticking point.

            The rest of the Bolden soundbite doesn’t negate Bolden’s foremost priority being to make Muslims feel good about themselves, and if he has changed his foremost priority since 2010, I missed it in the news.

            I don’t see anything wrong with organizing international collaboration, either. But organizing international cooperation doesn’t require making NASA’s foremost priority making Muslims feel good about themselves.

          • Grafton Is Dust

            What is it about Muslims that you dislike, by the way? I’ve noticed that you’ve really homed-in on one comment amidst a fairly lengthy interview. Are you angry that NASA is committing resources to improving less-fortunate countries?

          • Debbie

            The part of the lengthy interview that was shocking and made headlines was in the clip. NASA trying to make Muslims feel good about themselves will do nothing to improve any less-fortunate country or advance any American interests, and is a shockingly ridiculous thing for its administrator to make his foremost priority. There would be no point in me getting angry about it, though — I actually find it mildly amusing.

            I don’t dislike anybody including any Muslim that doesn’t give me good reason to, but I do dislike Islamic ideology, mostly because I belong to multiple demographics which all mainstream versions of Islam relegate to the status of legitimate target for execution, mayhem, exploitation and oppression. But I realize that many if not most Muslims don’t take the most violently bigoted koranic “revelations” of Mohammed (MAPSBUh) seriously, if they are even aware of them.

          • Grafton Is Dust

            Such is the problem with a lot of religion; adherence varies.

            I haven’t seen NASA put any significant effort into this objective in the last six years though, and it hasn’t appeared to impact their budget to any significant degree judging by their annual pledges to Congress for funding. In fact, the idea seems to solely exist in that one interview.

            An anomaly, t’be sure.

          • Farmer with a Dell

            Yep, probably just an anomaly. ‘Course if NASA Administrator Bolden had stated as his foremost priority making us old WASP guys feel good about ourselves, well now, that would have been grounds for immediate termination without appeal, right there. I mean, it wouldn’t have harmed space exploration (we’d still have a Mars Rover and all that) but it would have permanently set the Affirmative Action Program back at least 75 years. So, we’re darned lucky Bolden hewed true to the talking points on that one, eh?

          • Grafton Is Dust


          • Farmer with a Dell

            Yep, WASP (White Anglo Saxon Protestant) male and not embarrassed to be…in spite of all the political correctness of reverse discrimination these past several decades. As we are becoming a minority around here, when will it be OK to search out our roots and take pride in our heritage? What shall we call ourselves, Anglo-Americans?

          • Grafton Is Dust

            I have no idea what you’re going on about mate, but I’m Anglo, you’re American. Only in America does one’s distant heritage seem to be so important.

            Can’t comment on whether you’re a minority, and honestly don’t care either way.

  • Jack Kalpakian

    There will be a Mars colony … in 300 to 500 years.

    • lab seven

      Yes, by then we should be smart enough to live in stupid places.

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