Mars Exchange
Planetary Protection: Preventing contamination of Mars

Planetary Protection: Preventing contamination of Mars

by Vince on Thursday, 8th September 2016 in Expert Opinions, People, John Rummel

Dr. John D. Rummel, an adviser to Mars One, is a Senior Scientist with the SETI Institute and was formerly the Director of East Carolina University’s (ECU’s) Institute for Coastal Science and Policy. He has served twice with NASA—from 1986 to 1993 as (among other things) Exobiology Program Manager and Manager, Life Support Systems Integration, and from 1998 to 2006 as NASA’s Planetary Protection Officer. From 2006 to 2008 he was NASA’s Senior Scientist for Astrobiology, responsible for all of NASA’s efforts in astrobiology. He chaired The International Council for Science’s Committee on Space Research (COSPAR) Panel on Planetary Protection from 1999 to 2014, and is also a member of COSPAR’s Panel on Exploration and the representative of the International Union of Biological Science on the COSPAR Council. He is the lead author of some of the newest guidelines on the exploration of Mars, “A New Analysis of Mars ‘‘Special Regions’’: Findings of the Second MEPAG Special Regions Science Analysis Group,” published in 2014 in Astrobiology.

Early this year, I spoke with Dr. Rummel about the concept of planetary protection and why we need to be especially careful as we explore and look to the possibility of settling Mars. In this final of three parts, we explore the risks of contamination and how the Mars One habitat can play a role in mitigating those risks.

What are the risks of contaminating Mars and how should these influence Mars One?

“In a paper that we published in the Journal, Astrobiology (November, 2014), we listed what we called “Special Regions” on Mars where we think Earth life could survive and grow. We really can’t leave microbes behind, because we don’t control clean room environments well enough to eliminate any microbes on Earth. In fact, what we do know is that clean rooms tend to select for organisms that are capable of dealing with harsh environments—more so than non-clean rooms. If you turn on a bunch of UV light, use bleach, do those sorts of things, you do not end up with zero microbes. You end up with microbes that are UV resistant and can handle bleach.

So there’s a kind of conundrum: The cleanest places we know, where we like to put together space craft, may not have too much dust, but microbes can tolerate them. And on the other hand, the easiest way for microbes to get into a spacecraft is on dust particles. But the dust provides them with food while protecting them from things like UV radiation.

When we think about contaminating Mars, we believe that two critical things limit the interaction of Earth microbes with Mars: cold and moisture. If it isn’t too cold (>-18C) or too dry (aw of >0.6) that would be a Special Region. Mars is really cold most of the time and in most places. And when it isn’t too cold, it’s usually too dry. We measure water activity (water availability) on a scale of zero to one. On that scale, the driest environment in which a terrestrial microbe has been found to replicate is 0.6. Most places on Mars, the water activity during the daytime is much lower than that. But we believe it is warm enough during the day on Mars for microbes to replicate, but there is not enough available moisture at those times. Meanwhile, at night, there is more moisture available, but it is too cold for replication. But we don’t know if there are microbes that can absorb the water overnight and then reproduce when it gets warm enough during the day.

We’ve seen frost on Mars, and instruments on the Phoenix lander detected snowfall, although we haven’t visually confirmed that. The frost occurs when it gets cold enough that the atmosphere can’t hold moisture and it freezes out onto the cold rocks. We think that the potential for the frost to turn into liquid water is very low. But when it snows, that can produce the potential for a limited liquid water supply.

We do know that there are lichens on the Earth that can use atmospheric moisture for metabolism. We’ve not yet seen lichen on Earth that can actually replicate using only atmospheric moisture. We don’t see a theoretical reason why that’s not possible, we just haven’t seen an organism that does that.

At any rate, when we think about putting people on Mars, we’d like to avoid contamination of Special Regions so that we don’t have Earth microbes confusing our science on Mars. We’d like to make sure we understand the exposure of human crew to areas of Mars that might be special and might have Mars life. No reason to blunder into that.

It’s easy to imagine that a place that Earth microbes would like would be a place that Mars microbes would like. But we have nothing other than our own prejudice to guide us there.  We do have the idea that if something were to live in some of the Special Regions, they might be closer to the sort of microbes we worry about in terms of our own potential contamination. That is, would they ruin our water supply or food supply or whatever?

We are learning more about Mars all the time. But the fact is, we just don’t really understand the Martian environment, especially on the microbial scale, which is much smaller than most of us can conceptualize. On Earth, microbes can live in a mixture of rock with occasional water. Microbes want to make more microbes. So some will look for organisms that can live on carbon dioxide and hydrogen. That organism will be putting together carbon compounds that they can eat. On Earth we have organisms that release methane, and others that take up methane and release higher-order compounds. So there’s lots going on, and one of the problems of dealing with the microbial environment is that we can only grow about one percent of the microbes that live on Earth. This means we have a very limited knowledge of the behavior of things that we can name. Using DNA and RNA evidence, we can identify large numbers of microbes, but we really have no idea—or at best, a limited idea—of what they do.

Looking at the complexity of the microbial world on Earth, you could see that we would have a concern that there could be systems of life on Mars that we would be unable to detect, let alone understand. In particular, Mars gets relatively warm and wet every 50,000 years; it probably snows on the equator at those times. So during those periods you have the potential for a different kind of Mars than we see today. One of the fascinating places on Mars—a place we don’t go to due to high winds and other difficulties—is the Hellas Basin. This basin is low, so the air pressure is much higher than the areas we’ve been going.  There’s potential for liquid water, briny or otherwise, that may not be evaporating away.

Mars One will need to have missions that address these questions on a broader scale. They will need to determine if there are areas we might go to that we should be concerned about. Mars One can make some very focused measurements of the kind that had been proposed by the European Space Agency with their Aurora program. The basic tests to look for life can be done relatively cheaply. Mars One may be in a much better position to do these tests than some of the agencies. A robotic campaign upfront could do some of this, and without such a campaign, Mars One would be dancing in the dark. Some basic measurements, similar to those recommended in the report, Safe on Mars (2002) suggested things we should measure.

You’d like to land in an area with subsurface ice. Easy access to water is key for a landing site. All you have to do is melt that to get at the hydrogen you need to operate your life support system. A lot of people talk about heating up soil to get at the water, but that’s more energy intensive than melting ice. The problem is that the ground ice is not close to the equator, where it is easier to operate photovoltaics.

If Mars One develops a working life support system, it means you understand the importance of recycling and containment. In an open system, you can just throw stuff out the door, then you are more likely to contaminate Mars. But if you look at each bit of human waste as a future green salad, you have a different approach that also protects Mars against contamination by recycling waste.

To recap, Mars One needs to consider the potential that there is Mars life and how to approach it. Accidentally distributing Earth microbes on Mars may have implications beyond the destruction of science and into the potential degrading of the very environment that Mars settlers would like to depend on. And I think that they need to understand the implications of what they do for the future of human exploration of Mars. Dealing with Mars involves making choices on a very fine scale about how Earth microbes and other contaminants might be introduced—at the same time that the Mars One astronauts have to defend themselves against the known hazards of the Martian environment, like radiation, lack of breathable air, and so forth. If they want to be effective in living on Mars, they will need to go in and out of the habitat. That’s a real challenge. If they can’t do that in a robust manner, they’ll have less likelihood of survival.

The important thing is that Mars One understands how the settlers will interact with Mars. They will be breaking down barriers between humans and the planet whether they want to or not. And they will need multiple solutions to what happens in those interactions. Otherwise, Mars will win.”

Story submitted by Vincent Hyman, a writer and Mars One volunteer living in St. Paul, Minnesota, USA. 

Also read the previous two stories on Planetary Protection:

Planetary Protection: Keeping Mars safe for Martians

Planetary Protection: How would the discovery of Martian life impact Mars One?

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