MIT study humans could only suvive 68 days on Mars

[dragon]

The actual study link

n 2012, the “Mars One” project, led by a Dutch nonprofit, announced plans to establish the first human colony on the Red Planet by 2025. The mission would initially send four astronauts on a one-way trip to Mars, where they would spend the rest of their lives building the first permanent human settlement.

It’s a bold vision — particularly since Mars One claims that the entire mission can be built upon technologies that already exist. As its website states, establishing humans on Mars would be “the next giant leap for mankind.”

But engineers at MIT say the project may have to take a step back, at least to reconsider the mission’s technical feasibility.

The MIT researchers developed a detailed settlement-analysis tool to assess the feasibility of the Mars One mission, and found that new technologies will be needed to keep humans alive on Mars.

For example, if all food is obtained from locally grown crops, as Mars One envisions, the vegetation would produce unsafe levels of oxygen, which would set off a series of events that would eventually cause human inhabitants to suffocate. To avoid this scenario, a system to remove excess oxygen would have to be implemented — a technology that has not yet been developed for use in space.

Similarly, the Mars Phoenix lander discovered evidence of ice on the Martian surface in 2008, suggesting that future settlers might be able to melt ice for drinking water — another Mars One goal. But according to the MIT analysis, current technologies designed to “bake” water from soil are not yet ready for deployment, particularly in space.

The team also performed an integrated analysis of spare-parts resupply — how many spare parts would have to be delivered to a Martian colony at each opportunity to keep it going. The researchers found that as the colony grows, spare parts would quickly dominate future deliveries to Mars, making up as much as 62 percent of payloads from Earth.

As for the actual voyage to Mars, the team also calculated the number of rockets required to establish the first four settlers and subsequent crews on the planet, as well as the journey’s cost.

According to the Mars One plan, six Falcon Heavy rockets would be required to send up initial supplies, before the astronauts’ arrival. But the MIT assessment found that number to be “overly optimistic”: The team determined that the needed supplies would instead require 15 Falcon Heavy rockets. The transportation cost for this leg of the mission alone, combined with the astronauts’ launch, would be $4.5 billion — a cost that would grow with additional crews and supplies to Mars. The researchers say this estimate does not include the cost of developing and purchasing equipment for the mission, which would further increase the overall cost.

Olivier de Weck, an MIT professor of aeronautics and astronautics and engineering systems, says the prospect of building a human settlement on Mars is an exciting one. To make this goal a reality, however, will require innovations in a number of technologies and a rigorous systems perspective, he says.

“We’re not saying, black and white, Mars One is infeasible,” de Weck says. “But we do think it’s not really feasible under the assumptions they’ve made. We’re pointing to technologies that could be helpful to invest in with high priority, to move them along the feasibility path.”

“One of the great insights we were able to get was just how hard it is to pull this [mission] off,” says graduate student Sydney Do. “There are just so many unknowns. And to give anyone confidence that they’re going to get there and stay alive — there’s still a lot of work that needs to be done.”

Do and de Weck presented their analysis this month at the International Astronautical Congress in Toronto. Co-authors include MIT graduate students Koki Ho, Andrew Owens, and Samuel Schreiner.

Simulating a day on Mars

The group took a systems-based approach in analyzing the Mars One mission, first assessing various aspects of the mission’s architecture, such as its habitat, life-support systems, spare-parts requirements, and transportation logistics, then looking at how each component contributes to the whole system.

For the habitat portion, Do simulated the day-to-day life of a Mars colonist. Based on the typical work schedule, activity levels, and metabolic rates of astronauts on the International Space Station (ISS), Do estimated that a settler would have to consume about 3,040 calories daily to stay alive and healthy on Mars. He then determined crops that would provide a reasonably balanced diet, including beans, lettuce, peanuts, potatoes, and rice.

Do calculated that producing enough of these crops to sustain astronauts over the long term would require about 200 square meters of growing area, compared with Mars One’s estimate of 50 square meters. If, as the project plans, crops are cultivated within the settlers’ habitat, Do found that they would produce unsafe levels of oxygen that would exceed fire safety thresholds, requiring continuous introduction of nitrogen to reduce the oxygen level. Over time, this would deplete nitrogen tanks, leaving the habitat without a gas to compensate for leaks.

As the air inside the habitat continued to leak, the total atmospheric pressure would drop, creating an oppressive environment that would suffocate the first settler within an estimated 68 days.

Possible solutions, Do says, might include either developing a technology to extract excess oxygen or isolating the crops in a separate greenhouse. The team even considered using nitrogen extracted from the Martian atmosphere, but found that doing so would require a prohibitively large system. Surprisingly, the cheapest option found was to supply all the food required from Earth.

“We found carrying food is always cheaper than growing it locally,” Do says. “On Mars, you need lighting and watering systems, and for lighting, we found it requires 875 LED systems, which fail over time. So you need to provide spare parts for that, making the initial system heavier.”

Twisting the knobs

As the team found, spare parts, over time, would substantially inflate the cost of initial and future missions to Mars. Owens, who assessed the resupply of spare parts, based his analysis on reliability data derived from NASA repair logs for given components on the ISS.

“The ISS is based on the idea that if something breaks, you can call home and get a new part quickly,” says Owens. “If you want a spare part on Mars, you have to send it when a launch window is open, every 26 months, and then wait 180 days for it to get there. If you could make spares in-situ, that would be a massive savings.”

Owens points to technologies such as 3-D printing, which may enable settlers to manufacture spare parts on Mars. But the technology as it exists today is not advanced enough to reproduce the exact dimensions and functions of many space-rated parts. The MIT analysis found that 3-D printers will have to improve by leaps, or else the entire Mars settlement infrastructure will have to be redesigned so that its parts can be printed with existing technology.

While this analysis may make the Mars One program look daunting, the researchers say the settlement-analysis tool they’ve developed may help determine the feasibility of various scenarios. For example, rather than sending crews on one-way trips to the planet, what would the overall mission cost be if crews were occasionally replaced?

“Mars One is a pretty radical idea,” Schreiner says. “Now we’ve built a tool that we can play around with, and we can twist some of the knobs to see how the cost and feasibility of the mission changes.”

Tracy Gill, a technology strategy manager at NASA, says the tool may be applicable for assessing other missions to Mars, and points to a few scenarios that the group may want to explore using the settlement-analysis tool.

“This [tool] can provide a benefit to mission planners by allowing them to evaluate a larger spectrum of mission architectures with better confidence in their analysis,” says Gill, who did not contribute to the research. “Included among those architectures would be options ranging from completely growing all food in situ with bioregenerative systems, to packaging all food products from Earth, to various combination of those two extremes.“

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[Borgholio]

Some form of oxygen removal system is required, a technology that has not yet been developed

Start a fire? That removes oxygen and has been around for a million years. A small flame could consume a great amount of oxygen. Might not work on the spacecraft of course, but on the surface it should be safe.

[GrandMasterTerwynn]

Some form of oxygen removal system is required, a technology that has not yet been developed

Start a fire? That removes oxygen and has been around for a million years. A small flame could consume a great amount of oxygen. Might not work on the spacecraft of course, but on the surface it should be safe.

Oxygen which you are then replacing with carbon dioxide and water vapor, which costs still more energy to scrub from the air. This is in addition to the fact that you're going to need something to burn, if you're going to be burning off excess oxygen (i.e., you'll need to add a tank of methane, or something, which will cost mass and eat into the space and mass you'd devote to gasses needed to keep the habitat's atmospheric pressure up.) Not to mention fire would introduce excess heat to the habitat, which must then be removed.

You'd probably be better off using that oxygen-scavenging cobalt salt that some Danes just invented.

[InsaneTD]

Well the plants are scrubbing the CO2 from the air, you also can't use most of the material you get from the plant for food either which is then generating waste. You have two options for that waste, burn it, or compost it. Composting it produces gases and fertiliser. I can't remember the gases produced by composting, but I believe one is methane. Human waste will also need treatment and also produces gases, so fuel for burning won't be that hard to come by. There is also the option of adding fish to the system, a hydroponics system with integrated fish tanks means the fish waste feeds the plants, the plants filter the water. Fish use the oxygen and produce carbon dioxide. You also then have a source of animal proteins. Though the cost of sending the fish stock and water into space would be an issue.

[Simon_Jester]

Removing excess oxygen from the air sounds like a solvable problem- maybe not easy, but solvable. There is, for example, this stuff referenced in a thread a short distance down the page from here.

The real takeaway lessons here are:
1) The Mars One plan made excessively favorable assumptions about how easy some of this stuff would be. No surprise there.
2) New technologies still need to be developed for Mars colonization to work. Also no surprise there.
3) Maintaining a self-sufficient 'ecosystem' that produces food and oxygen is hard. No surprise there either; we knew that since Biosphere 2 at the latest.
4) Logistics for a Mars mission is tricky, and things like greenhouse facilities for growing your own food are considerably more bulky and temperamental than, say, a case of MREs. Again, no surprise there. Honestly I hadn't figured on such facilities being operational in a Mars colony until and unless that colony reached a population of several dozen at least, with more people coming and going every year and plenty of supply runs being needed as a matter of routine.

[Feil]

Two things for this. Not saying that its conclusions are wrong, but don't put too much faith in them.

First: none of the authors but Olivier de Weck (the last-mentioned supporting author) have Ph.D's and IAC isn't a peer-reviewed scientific journal. This is a conference paper written by a bunch of Ph.D candidates and grad students.

Second: "Some form of oxygen removal system is required, a technology that has not yet been developed for use in space"

The wording of this sentence has apparently confused several people in this thread... and is also bizarre. It correctly references the journal article, which itself is bizarre on that subject. Filtering oxygen from air under Earth-like pressure and gravity conditions is cheap, easy, reliable, and well-understood, with at least hundreds of thousands and perhaps millions of units in active use (hospitals, aircraft, industrial applications). Adjusting that technology for use in a pressurized habitat under Mars-like gravity will require very minor changes to a well-understood process. Adjusting that technology for use under zero-gravity presumably requires major changes and the development of new processes... which is completely irrelevant to a Mars habitat. I may not work at MIT, but I'm pretty sure a Mars habitat isn't in space, it's on Mars.

[Simon_Jester]

Hm. Sorry, should have looked for that.

[madd0ct0r]

the paper isn't clear, but the baseline flows in figure 3: suggest they aren't using oxygen to treat crew member waste or biomass residues.

[Nova Andromeda]

Interesting, we have an oxygen sucking crystal now apparently:
Oxygen sucking crystal (SDnet thread)

[Elheru Aran]

Geez. Guys, that's the *third* time that same link has been posted. I think we get the hint by now

As far as the leakage thing goes: Doesn't Mars have an atmosphere, however thin it is? Would it not be conceivably possible to use some form of air compressor to collect external air and put it to use in some fashion? A quick Google reveals that it's something like 96% carbon dioxide, which is to say the least somewhat unhealthy. Hmm.

If they're using inflatable domes, perhaps one could use the Martian air to inflate it rather than shipping expensive Earth air up there? As in, the dome is an inflatable shell, like a double-layered bubble? Though I can see how that might add to weight concerns...

[Borgholio]

Martian air is mostly CO2 but it is also very thin. They could pump it into a dome to inflate it and then put some plants in there to soak up the CO2.

[Elheru Aran]

That much CO2 might backfire on the poor little plants, though... I really don't know how good they are at absorbing it. Algae might do a little better.

[Borgholio]

Is it possible to asphyxiate a plant?

[Feil]

Too much CO2 has adverse effects on plants and can mess up their chemistry, which is obviously bad if we're going to be eating them. I'd guess that algae should fare better, although any water that stays in a 96% CO2 atmosphere for long is going to end up acidic from
CO2 + H2O <-> H2CO3 <-> H + HCO3
to the tune of about pH 4*. I'm pretty sure that there are some algaes that can grow at that pH, but most can't.

*at least at Earth-like pressures. I'm not sure how low pressure would affect it.

[Jub]

If the issue is the greenhouse over producing oxygen you should be able to exchange oxygen for CO2 just by setting up a vent and an intake. The vented oxygen can either replenish any lost oxygen from the habs, or be vented to Mar's atmosphere. Then you just have an automated system keep things in balance and when harvest time comes the people harvesting do it wearing air tanks as if they were exploring the surface. The air in the green house doesn't need to be great for humans as they shouldn't need to be in there very often so long as we don't introduce pests or fungus to the mix.

[Simon_Jester]

Good point. Also, I'm not sure if plants need a certain partial pressure of oxygen, and if so, what buffer gas pressure they need. It might be that we could just let the plants chug along in a 3-4 psi atmosphere of almost pure oxygen plus trace carbon dioxide. In which case we really could just vent unneeded oxygen out of the greenhouse whenever it becomes a problem.

On the other hand, if we need a buffer gas (so that total pressure of the atmosphere in the greenhouse is more than 3-4 psi), carbon dioxide is not acceptable, helium is expensive and leaks out, so it'd have to be nitrogen. You'd want some means of isolating out the oxygen before disposing of it, because otherwise you'd be losing buffer gas with each venting of oxygen.

Still, though, that's a solved problem.