Thawing Mars
Summary (Jan 22, 2001): Greenhouse gases might one day be used to warm the cold surface of Mars, and make the planet habitable for humans.
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Thawing Mars
By Henry BortmanTo say that Mars is a chilly place is a bit of an understatement. The mean annual temperature on the red planet is minus 55 degrees Celsius. It is far too cold for human habitation. Which explains why those who believe that humanity one day will establish colonies on Mars take very seriously the problem of how to warm the planet up.
Humans won't be building thriving communities on Mars any time soon. But that hasn't stopped scientists from trying to figure out how the task of turning up the Martian thermostat might be accomplished. At a recent
NASA-sponsored conference on
terraforming Mars, the topic was given a good deal of attention.
One solution is to pump enough greenhouse gases into the Martian atmosphere to create a runaway greenhouse effect. On Earth, the idea of a runaway greenhouse sets off alarm bells. But on Mars, say those who set their sights on terraforming, it's a plus. It simply means warming up Mars enough that all of the planet's available carbon dioxide (CO
2) evaporates into the atmosphere, where it can contribute to keeping the planet warm.
But there are two problems. First, even if all Mars's available CO
2 were coaxed into the atmosphere, it still wouldn't necessarily warm the planet enough to make it a comfortable place for humans, because no one knows just how much CO
2 is there. Second, the best way to get Mars to release its CO
2 spontaneously is, well... to warm it up. It's kind of a vicious cycle.
Margarita Marinova, an undergraduate student at MIT, believes she has an answer to both problems: use artificially created
perfluorocarbons (PFCs) to initiate the planetary warming process. Marinova has been studying the warming effects of PFCs, in collaboration with
Chris McKay, a member of the
NASA Astrobiology Institute at NASA Ames Research Center. McKay was one of the organizers of the terraforming conference at which Marinova presented the results of her research.
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| Sunlight is absorbed by a planet's surface, which then radiates warming infrared energy into the atmosphere. Greenhouse gases prevent that energy from escaping into space. Credit: NASA. |
PFCs have several advantages. First, they are super-greenhouse gases. A little bit does a lot of warming. Second, PFCs have a very long lifetime. This
causes serious problems on Earth, but would be a positive factor on Mars. Third, they do not have any negative effects on living organisms.
Finally, unlike their chemical cousins, chlorofluorocarbons (CFCs), PFCs don't deplete ozone. Ozone in Earth's atmosphere provides protection against ultraviolet (UV) radiation, which is harmful to life. On Mars, building up an ozone layer in the atmosphere there is only a miniscule amount at present would be an important goal of terraformers. "You don't want to destroy ozone," says Marinova, "because it's a UV protector."
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| An artist's conception of how a terraformed Mars, with an ocean spanning most of its northern hemisphere, might look from orbit. |
The sunlight that hits a planet's surface arrives primarily as visible and ultraviolet light. The planet absorbs this solar energy, and then radiates warming infrared energy back out into the atmosphere. Greenhouse gases in the atmosphere work as a global layer of insulation, trapping that infrared radiation and preventing it from escaping into space.
CO
2 and water are good at trapping some of this infrared energy, but not all of it. On Earth, there's so much CO
2 and water in the atmosphere that it doesn't matter if some infrared radiation escapes out into space.
But on Mars, terraformers will want to trap every bit of heat they can. A carefully chosen combination of PFCs could do the job quite handily. "When we first start warming Mars," explains Marinova, "we'll want to cover the whole spectrum" of thermal infrared radiation. "Once CO
2 is released, it will take over" part of the job, and PFCs will only need to be used to plug the gaps.
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| Though still an undergraduate student, Margarita Marinova is advancing our understanding of how to make Mars habitable for humans. Pictured with her is Phobos, a teammate from the Haughton-Mars expedition to the Arctic. Credit: The Mars Society. |
And how fast can Mars be heated up? "That depends," says Marinova, "on how fast we make the gases." According to rough calculations, "if you had 100 factories, each having the energy of a nuclear reactor, working for 100 years, you could warm Mars six to eight degrees." At that rate, to increase the average Martian temperature to the melting point of water it's about minus 55 degrees Celsius at present would take about eight centuries. Actually, it wouldn't take quite that long, Marinova points out, because her calculation "doesn't include the feedback effect of the CO
2" that would be released as Mars got steadily warmer. "Devising more efficient artificial super-greenhouse gases will also make it faster," Marinova adds.
What's Next
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| Artist's conception of an early, pre-terraforming outpost for human visitors to Mars. Painting by Mark Dowman. Credit: Dowman/JSC/NASA. |
Human habitation of Mars is a long way off.
NASA's current plan for exploring the red planet, which spans the next two decades, does not include even a pioneering human mission to Mars. By the time a permanent settlement is established on Mars one that can begin the task of terraforming the planet technological advances may make it possible to warm its atmosphere far more efficiently than is possible using the techniques being studied today by scientists like Marinova.
Related Links
More on this story
Super-Greenhouse Gases Analysis Details of Marinova's research.
NASA Warms to Living on Mars Coverage of NASA's October 2000 terraforming Mars conference. From Wired News.
Terraforming MarsMars terraformation Introduction to terraforming Mars. Includes excellent images.
Bringing Life to Mars Article by NASA astrobiologist Chris McKay from
Scientific American, March 1999.
Bringing Mars to Life Transcript of a public lecture given byChris McKay
, March 1999.
Mars, the Final Frontier Article
New Scientist, February 1994.
The Terraforming Information Pages A variety of resources on terraforming Mars.
Extensive Literature about Terraforming Chris McKay's suggested bibliography on terraforming Mars.
The Effects of PFCs on EarthHFCs, PFCs, & SF6 Emissions From the US Environmental Protection Agency's web site on global warming.
Glossary: Perfluorocarbons (PFCs) From the US Environmental Protection Agency's web site on global warming.
Human Exploration of MarsHuman Exploration and Development of Space NASA's plan for humans in space.
NASA Human Spaceflight: Exploring Mars and Beyond NASA efforts towards the human exploration of Mars.
Haughton-Mars Project The dry, cold plains of Devon Island in the Canadian Arctic are an Earth analog of conditions on Mars. Researchers study the Mars-like terrain and test technologies for future Mars exploration.
Mars Society Flashline Arctic Research Station A simulated Mars base on in the arctic. Provides the opportunity to test designs for a Mars habitat. Developed in coordination with the Haughton-Mars Project.
Note:
Mars Life : 2001-01-22
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Monday, January 22, 2001
