Terraforming of Mars

Artists conception of the process of terraforming Mars

Since the origin of the idea of terraforming, or changing a planet's environment to produce a world that is habitable by humans, one of the primary subjects of study for potential terraforming has been the planet Mars.

There is some scientific debate over whether it would even be possible to terraform Mars, or how stable its climate would be once terraformed. It is possible that over geological timescales—tens or hundreds of millions of years—if not prevented, Mars could again lose much of its water and atmosphere, possibly due to the same processes that reduced it to its current state; however, geological time scales are far longer than those needed for terraforming or subsequent climate maintenance. A potential problem is that much of the gases in the atmosphere were permanently swept away. Gases from sources other than Earth or Mars would need to be gathered, as relying on what Mars had could be disastrous as if humans were not careful, Mars could lose what's left of its natural resources. Thus, relying on gathering frozen gases from space would be more practical.

Background

It is thought that Mars did once have a relatively Earthlike environment early in its history, with a thicker atmosphere and abundant water that was lost over the course of hundreds of millions of years. The exact mechanism of this loss is still unclear, though several mechanisms have been proposed. The relatively low gravity of Mars likely contributed to the loss of lighter gases to space. The lack of plate tectonics on Mars is another likely factor, preventing the recycling of gases locked up in sediments back into the atmosphere. The lack of a magnetosphere surrounding Mars may have allowed the solar wind to contribute to eroding the atmosphere, although that effect is also active on Venus, but has not prevented that planet from having far greater atmospheric pressure than Earth. The lack of magnetic field and geologic activity may both be a result of Mars's smaller size allowing its interior to cool more quickly than Earth's, though the details of such processes are still not precisely clear. However, none of these processes are likely to be significant over the typical lifespan of most animal species, or even on the timescale of human civilization, and the slow loss of atmosphere could possibly be counteracted with ongoing low-level artificial maintenance activities.

Terraforming Mars would entail two major interlaced changes: building up the atmosphere and heating it. Since a thicker atmosphere of carbon dioxide and/or some other greenhouse gases would trap incoming solar radiation, and increased heat would in turn increase erosion and chemical activities on the surface, resulting in more outgassing and evaporation, the two processes would augment one another.

Adding heat

Mirrors made of thin aluminized PET film could be placed in orbit around Mars to increase the total insolation it receives. This would increase the planet's temperature directly, and also vaporize water and carbon dioxide to increase the planet's greenhouse effect. Directing such reflected sunlight near the polar caps would maximize the effectiveness of this method.

While producing halocarbons on Mars would contribute to adding mass to the atmosphere, their primary function would be to trap incoming solar radiation. Halocarbons (such as CFCs and PFCs) are especially powerful greenhouse gases, and are stable for lengthy periods of time in atmospheres. They could be produced by genetically engineered aerobic bacteria or by mechanical processors scattered across the planet's surface.

Changing the albedo of the Martian surface would also make more efficient use of incoming sunlight. Altering the color of the surface with dark dust, soot, dark microbial life forms or lichens would transfer a larger amount of incoming solar radiation to the surface as heat before it is reflected off into space again. Using life forms is particularly attractive since they could propagate themselves, once life forms exist that can survive and be metabolically active on Mars.

Thinking far into the future, (on the order of hundreds of millions of years) some scientists point out that the Sun will eventually grow too hot for Earth to sustain life, even before it becomes a red giant star. All main sequence stars brighten slowly throughout their lifetimes. As a result, Mars will warm up on its own, making terraforming easier. Alternatively, an already-terraformed Mars would provide an alternate home for sentient life if Earth becomes uninhabitable (see Space and survival).

Building the atmosphere

Artist's conception of a terraformed Mars centered on the Tharsis region. (credit: Daein Ballard)

Since ammonia is a powerful greenhouse gas, and it is possible that nature has stockpiled large amounts of it in frozen form on asteroidal sized objects orbiting in the outer solar system, it may be possible to move these (for example, by using very large nuclear thermal rockets for the purpose, using some of the ammonia itself as the reaction mass) and send them into Mars's atmosphere. Since ammonia is high in nitrogen (NH₃) it might also take care of the problem of needing a buffer gas in the atmosphere. However, impacting a comet onto the surface of the planet might cause destruction to the point of being counter-productive. Aerobraking, if an option, would allow a comet's frozen mass to outgas and become part of the atmosphere through which it would travel. It may be better to impact several smaller asteroids into the planet, both to build up the planet mass and to add to the atmosphere. Keeping these smaller impacts on their own will eventually build up the temperature as well as mass to both the planet and its atmosphere. In 1970 physicist Freeman Dyson proposed sending a self-replicating machine to Saturn's moon Enceladus, which in addition to producing copies of itself would also be programmed to manufacture and launch an enormous number of solar sail-propelled cargo spacecraft. These spacecraft would carry blocks of Enceladean ice to Mars. Another possibility is to use perfluorocarbons, because they too are a powerful greenhouse gas. To minimize the effect of any asteroids or comets impacting the planet, production of any greenhouse gas should be spread decentralized and distributed throughout the planet.

The need for a buffer gas is a challenge that will face any potential atmosphere builders. On Earth, nitrogen is the primary atmospheric component making up 77% of the atmosphere. Mars would require a similar buffer gas component although not necessarily as much. Still, obtaining significant quantities of nitrogen, argon or some other comparatively inert gas could prove difficult.

Hydrogen importation could also be done for atmospheric and hydrospheric engineering. Depending on the level of carbon dioxide in the atmosphere, importation and reaction of hydrogen would produce heat, water and graphite via the Bosch reaction. Adding water and heat to the environment will be key to making the dry, cold world suitable for Earth life. Alternatively, reacting hydrogen with the carbon dioxide atmosphere via the Sabatier reaction would yield methane and water. The methane could be vented into the atmosphere where it would act to compound the greenhouse effect. Presumably, hydrogen could be obtained in bulk from the gas giants or refined from hydrogen-rich compounds in other outer solar system objects, though the energy required to transport large quantities would be great.

Simply thickening the Martian atmosphere will not make it habitable for Earth life unless it contains the proper mix of gases. Achieving a suitable mixture of buffer gas, oxygen, carbon dioxide, water vapor and trace gases will entail either direct processing of the atmosphere or altering it by means of plant life and other organisms. Genetic engineering would allow such organisms to process the atmosphere more efficiently and survive in the otherwise hostile environment.

Artist's conception of a terraformed Mars. This realistic portrayal is approximately centered on the prime meridian and 30 degrees north latitude, and a hypothesized ocean with a sea level at approximately two kilometers below average surface elevation. The ocean submerges what are now Vastitas Borealis, Acidalia Planitia, Chryse Planitia, and Xanthe Terra; the visible landmasses are Tempe Terra at left, Aonia Terra at bottom, Terra Meridiani at lower right, and Arabia Terra at upper right. Rivers that feed the ocean at lower right occupy what are now Valles Marineris and Ares Vallis, while the large lake at lower right occupies what is now Aram Chaos. (credit: Daein Ballard).

Building a shield against radiation

Another significant, and probably most over-looked aspect of terraforming Mars, would be the lack of a magnetosphere. The magnetosphere deflects most of the hard particulate radiation from the solar wind. Without some form of radiation protection, anyone on Mars would have prolonged exposure to an unhealthy amount of radiation every time a serious solar eruption occurred. Terraforming involves making life viable on another world, and so long as that life is going to be exposed to high levels of radiation it will not be desirable. The lack of a magnetosphere is also thought to have caused the Martian atmosphere to become as thin as it is in the first place, the solar wind adding a significant amount of heating to the atmosphere's top layers which enables the atmospheric particles to reach escape velocity and leave Mars (more or less boiling off the newly formed atmosphere). Indeed, this effect has even been detected by Mars-orbiting probes. Venus, however, shows that the lack of a magnetosphere does not preclude an atmosphere. A thick atmosphere will also provide radiation protection for the surface, as it does at Earth's polar regions where aurorae form, so in the short term the lack of a magnetosphere would not seriously impact the habitability of a terraformed Mars.

On a longer timescale, and with the technology of the near future (in perhaps 250-500 years), an artificial magnetosphere seems possible: If the energy of several large fusion power stations is used to power large superconducting magnets - the field should be strong enough to protect at least local settlements. However, recent scientific evidence suggest that just a thick enough atmosphere like Earth's is enough to create a shielding effect in the absence of a magnetosphere. In the past, Earth regularly had periods where the magnetosphere changed direction and collapsed for some time. Some scientists believe that in the ionosphere, a magnetic shielding was created almost instantly after the magnetosphere collapsed, a principle that applies to Venus as well and would also be the case in every other planet or moon with a large enough atmosphere.

The New Life

A new planet is a prospect that no other human species has yet had to think of. Dreamed of, though of, yes, the greatest minds in history have longed though of this. But so far, we are the only human species that has ever really had the chance to actually explore a new planet, and getting to Mars is far harder than anyone has ever thought of.

But lets skip that and get into the best part, and that is what humans will do and look like on the new planet. Scientist are currently working on a rocket that will take you to Mars in only 90 days. While this may seem like a long time, it truly is almost no time at all when you considerer the distance. But once arrived there, humans will have already greatly transformed Mars. There will be green fields that scientist will have planted to produce oxygen, an atmosphere to retain heat, rivers of water that formed from the ground that melted since the atmosphere warmed up, animals that have evolved from the bacteria that scientist have brought from Earth, and of course, a dome building to house Mars newest citizens.

See also

• Colonization of Mars
• Terraforming of Venus
• Total Recall, an American science fiction film from 1990; an example of popular culture speculation regarding the terraforming of Mars.

External links

• Recent Arthur C Clarke interview mentions terraforming
• Red Colony
• Terraformers Society of Canada
• Research Paper: Technological Requirements for Terraforming Mars
• Peter Ahrens The Terraformation of Worlds
• MARSDRIVE: Colonizing Mars. Red Colony parent organization planning the future exploration and colonization of planet mars.
• Mars Reborn, a portrait of a possible Mars one thousand years from now, by Chris Wayan, 2003