QUESTION: Is it possible to colonize mars to the extent that human beings could live there? If so, then how would you go about it? Would we ever need to colonize Mars? ANSWER from R. Bourke on January 9, 1997: It may be possible for people to live on Mars in the future, but they must be protected from the environment. Conditions on Mars are much more harsh than any on Earth. It is very cold--far below freezing--there is no water, and the air is very thin and mostly carbon dioxide. Thus people will not be able to breath the air without space suits. In fact, machinery must be used to decompose the carbon dioxide to separate the oxygen to produce breathable air. ANSWER from Jack Farmer on January 30, 1997: The colonization of Mars by humans is being thought of in terms of "terraforming", which simply means modifying the Martian atmosphere and climate to make the "red planet" habitable for life. The Surface Environment of Mars: Cold, Dry and Full of Radiation The present surface of Mars is an inhospitable place for any terrestrial life form, whether microbe or person. The atmospheric pressure averages about 7.5 millibars (the avg. for Earth is 1000 mb). This means that water is unstable and can exist only as ice or vapor at the surface. In addition, the thin atmosphere of Mars is composed almost entirely of carbon dioxide (95%) and it lacks the oxygen needed to support human colonists without creating airtight shelters or spacesuits filled with our kind of atmosphere. The lack of oxygen also poses another risk. There is no protective ozone shield and the surface gets a very heavy dose of ultraviolet radiation (3-4X that at the Earth's surface). We know that UV is harmful to most life forms (that's why we have to use sunscreen!). As far as we know, Mars lacks a magnetic field, and that means that lots of other harmful radiation reaches the surface of Mars from the sun that, on Earth, is deflected away from the surface by the magnetic field. The temperature of the Martian surface is below freezing most of the time over most of the surface. Lastly, Mars is very cold (mostly below freezing most everywhere), but humans are able to live in cold climates on Earth, so that is not an insurmountable problem. However, combined with everything else, it makes colonization a real challenge. Building a Martian Atmosphere: An Oxygen-rich Greenhouse Terraforming would involve increasing the atmospheric density of Mars by liberating the water and carbon dioxide that lies frozen in the soils and on the polar caps of Mars to create a "greenhouse" effect (carbon dioxide and water both absorb heat energy from the sun and retain it causing the atmosphere to warm up) that would raise the surface temperature to the point where liquid water would be stable. There are a number of ideas for how to do that, but most involve installing large atmosphere-producing plants on Mars that would pump out carbon dioxide and perhaps other greenhouse gases like methane continuously until the atmiosphere was built up to the right level. Obviously, at some point we would also want to add oxygen to make the atmosphere breathable. On Earth, oxygen in our atmosphere is almost entirely formed by photosynthesis of green plants. So during terraforming, sometime after water ahd been rendered stable by the increased atmosphere, we would introduce photosynthesizing plants to contribute oxygen. What other benefit do you think oxygen would add, based on the preceeding discussion? There are a number of people and approaches that have been suggested for terraforming. Additional Reading: Some of these ideas were reviewed in a recent book by Robert Zubrin titled "The Case for Mars: The Plan to Settle the Red Planet and Why We Must" (1996, Free Press Publishing). Jack D. Farmer, PhD. NASA Ames Research Center ANSWER from Mark Adler on June 20, 1997: Yes. But it won't be easy. Mars is deathly cold (around minus 100 F), has a very thin carbon dioxide atmosphere with almost no oxygen, and has no ready supply of water. You'd have to *really* want to live there. A few people could be sustained on Mars with a steady line of supplies coming from Earth. In the long term, decades, we could find ways to provide some of those supplies on Mars, allowing the small colony to become more and more self-sufficient over time, and to possibly even grow. It would be a very long time, perhaps a century or more, before a colony on Mars could be completely independent. On even longer time scales, a few centuries, some people believe that we could change Mars globally to make it more hospitable for people by somehow making the atmosphere thicker and warmer. ANSWER from Mark Adler on July 29, 1997: There is certainly the possibility of humans exploring Mars. It's simply a matter of the rather high cost. Mars' atmosphere is extremely thin (less than 1/100th as thick as our atmosphere), is composed mostly of carbon dioxide, and is very cold. In short, Mars' atmosphere cannot support humans or other Earth life. However, that does not mean that we cannot inhabit the planet someday. We would need special enclosures to contain a warm, Earth-like atmosphere to live in. Mars' atmosphere of carbon dioxide and some nitrogen can be used, with some machinery and electrical power, to create and replenish an oxygen/nitrogen atmosphere in the enclosures. Water is a bit more of a problem, but there may be solutions there as well. Some people talk about actually changing Mars' atmosphere on a global scale to make it thicker and warmer in order to make habitation easier This is inspired in part by human's inadvertent but noticeable effect on Earth's atmosphere. However, it will likely be a long time before we have the technology and sheer presence to make global changes on Mars. Mark Adler ANSWER from Jim Murphy on June 22, 1998: I do not think that humans will NEED to colonize Mars, but I believe that we will have a very strong desire to do so since it is a challenge to be met (like going to the moon was..). I don't believe that current and future environmental problems we must deal with here on Earth are a good argument for developing a Mars colony. Rather, I'd prefer that we deal with our problems here. If we can develop the technology to build and sustain a Mars colony, then we can certainly develop strategies to deal with our problems here on earth without running (or rocketing) away to another planet. I certainly think that a Mars colony is possible. I would not expect one to be developed/built prior to 50-100 years from now, unless some form of life is discovered there, which would greatly accelerate the desire to get a base established. The cost will be enormous, and currently neither the money nor political will exists to fund the effort, but there are people thinking about how to do it. The advantages to having a Mars colony are to be able to conduct long-term science studies there, and to be able to travel over large distances on the surface repeatedly. Since the day length on Mars is 24 hours and 36 minutes, I would think it would be no problem to adjust to that day length. A colony would need to be "self contained", that is a structure not directly opened to the Martian atmosphere, since the Martian atmosphere is not capable of sustaining people (the lack of oxygen, and low atmospheric pressures would be deadly to anyone directly exposed to the atmosphere). Weather would play a role in determining how people travel about on the surface. Being out during a dust storm might make determining which direction to go difficult, and the large winds which might sometime blow could be a problem for some of the structure. ANSWER from Donna Shirley on July 9, 1998: I don't think humans "need" to colonize Mars in the sense that colonizing Mars will save us from the affects of overpopulating or despoiling the earth. If we get into such a situation I don't think that we will be able to afford to colonize a planet so far away. I think we "need" to explore Mars from the standpoint that we are a curious, exploring species. Donna Shirley