Terraforming Mars

The Planetary Engineering of Mars

"Terraforming is the process of planetary engineering, specifically directed at enhancing the capacity of an extraterrestrial planetary environment to support life. The ultimate in terraforming would be to create an uncontained planetary biosphere emulating all the functions of the biosphere of the Earth-one that would be fully habitable for human beings." – M.J. Fogg, Terraforming: Engineering Planetary Environments, SAE International (1995)

“Terraform” was actually a concept from the mind of science fiction writer Jack Williamson, under the pseudonym Will Stewart, in a series of stories published in the 1940’s (Lewis, 923). I will be using the terms terraforming and planetary engineering (coined by Carl Sagan in the 1970’s) interchangeably. I’ll focus chiefly on proposals by which clement temperatures can be achieved on biome and global scales. Evidenced by the ozone depletion and global warming, humans are known to have the capability to alter environments on a planetary scale. Future technologies can help us to utilize that capability in a more responsible and intentional manner.

This essay discusses terraforming as a means of creating and maintaining habitable environments on Mars, mostly within the boundaries of existing technological knowledge. Mars is usually considered to be the most likely candidate for terraforming. The foremost challenges involved with planetary engineering are funding for the various projects, and being restricted by our modern technology. Despite these confines, much study has been done concerning the possibility of heating Mars and altering its atmosphere in order to support life. Nonetheless, any planetary engineering scheme that takes more than several decades to achieve significant results should be rejected on grounds that policies and investors change too easily, and it might end up an uncompleted waste of money.

First, a bit about Mars itself and the climate we aim to alter to suit our needs. Evidenced by extensive fluvial features observable on the surface, it is believed that the warm climate on primitive Mars was created by a strong greenhouse effect caused by a thick CO2 atmosphere (Traicoff, et al.). The discovery of water-formed minerals on Mars (hematite and jarosite found by the Opportunity rover, and goethite found by the Spirit rover) has led to the conclusion that climatic conditioning in the distant past allowed for liquid water on its surface. In addition, a study concluded in 2013 that mars might have had an oxygen-rich atmosphere billions of years ago (Matsos, et al.).

Mars lost most of its magnetosphere about four billion years ago, stripped by solar winds. This left the surface exposed to incoming radiation. Direct interaction between solar winds and cosmic radiation leave the atmosphere worn thin, and low gravity allows some of the Martian atmosphere to escape into space. The atmosphere of Mars is mostly composed of CO2 but methane has also been detected in trace amounts. Methane could be an indicator of life on a planet, however, in the case of Mars the methane likely originated from the volcanoes that were once active in Mars’ past. The Tharsis volcanoes on Mars were active billions of years ago and ejected water vapor and carbon dioxide into the atmosphere creating a warmer climate similar to that of Earth’s (Zubrin, et al.).

Mars is smaller and farther away from the sun than Earth. A unit area on Mars absorbs roughly half the solar flux as an identical area on Earth (Lewis, 924). The atmospheric pressure on Mars is about 0.6% that of Earth’s average sea level pressure, and this pressure is well below the Armstrong limit for what the unprotected human body can withstand (Matsos, et al.). Mars became colder when most of its volatile CO2 was fixed into the carbonate rock. Although, it has been speculated that some of the volatile CO2 may still be trapped in the ice on the poles. That means a warming event could trigger the release of this trapped greenhouse gas, and could spur a positive feedback loop accelerating the warming, much like on Earth.

Average temperatures on Mars are around 218K (-55℃, -67℉). For global environments suitable for plants and animals including humans, requires modifying the atmospheric composition in order to increase depth and pressure, which would thereby increase the surface temperature. We require gases that not only are effective infrared absorbers, but also that remain in the gas phase at Martian temperatures. Below I’ll discuss three candidate gases NH3, CO2, and halogen compounds.

If scientists were somehow able to test their hypotheses about global warming on Mars, maybe we could find a way to reverse the process on Earth. Global warming on Earth has led to calls for mitigation, often by planetary engineering- e.g., emplacement and replenishment of reflective or anti-greenhouse layers at high altitudes, or sunshields that are deployed in space (Lewis, 921). And yet, scientists have known for years that combating deforestation would be the safest and most cost effective way to reduce global warming. So as for planetary engineering, first there must be increased research and development projects to find technologies that would apply, and to work on a plan for funding such enormous long-term projects.

A proposal has been to induce the greenhouse effect trapping the sun’s energy within the atmosphere. It is estimated that taking advantage of this positive feedback of warming through greenhouse effect would reduce the requirements for planetary engineering by two orders of magnitude. This method could be employed several different ways, each I will explain in some detail.

Mars harbors all the elements necessary to support life: water, carbon, oxygen (as carbon dioxide), and nitrogen. The problem lies in releasing these elements from the ice they are stored in. Enormous quantities of CO2 and H2O are locked in the polar caps. With the amount of CO2 and H2O in the polar cap, if released into the atmosphere would probably produce much more Earth-Like climatic conditions. Except there’s a catch: the available CO2 from the polar cap falls short of the required abundance by more than an order of magnitude (Lewis, 929).

The three most promising options for inducing the required temperature rise to produce a runaway greenhouse on Mars appear to be the following: 1.) Use orbital mirrors to aim high-energy solar beams at the poles of Mars to melt the ice and release stored greenhouse gases. 2.) Import greenhouse gases from elsewhere in the solar system for example the ammonia stored in asteroids from the outer solar system. 3.) Set up factories to pump out large quantities of powerful greenhouse gases such as halocarbons (CFC’s). All of these methods used in conjunction would be ideal, but also very costly. I’m somewhat confident that in the future we’ll find out how to lower the cost of technologies required for space travel.

Sagan suggested that we might simply sprinkle the caps with a 1mm thick layer of carbon black, which would absorb sunlight thereby heating up the Martian poles. The polar ice cap is 350 km in diameter, and Sagan found that at least 0.1 km3 of material weighing 2x1011 kg would be required. However, the cost of such a mission would be exceedingly expensive, one to two hundred billion is probably a conservative estimate

The so-called orbiting mirror method was proposed in a study conducted at the NASA Ames Research Center by Zubrin and Mckay. It found that a 5 degree Kelvin temperature rise at the poles should be sufficient to cause the evaporation of CO2. Based on the total solar energy required, they found that a space-based mirror with a radius of 125 km could reflect enough to accomplish such a task, and that the required operating altitude should be 214,000 km (Zubrin, et al.).

Another suggested method for terraformation is the harnessing of asteroids for their stockpiles of ammonia, a precursor for the greenhouse effect. This is assuming that fusion power will provide us with the technology to move asteroids at will. It might be easier to instead search for these asteroids in the outer solar system rather than inner due to the orbital velocity being slower farther away from the sun. One asteroid that we’ve detected is named Chiron. Chiron is orbiting between Saturn and Uranus and is likely to be composed of frozen gases like ammonia.

Aside from asteroids, nitrogen-fixing microorganisms are abundant on Earth and they too are a source of ammonia. Unfortunately, ammonia disassociates in UV light so it wouldn’t help to pump ammonia into the Martian atmosphere unless it was already sufficiently thick to block out UV radiation.

The New Horizons mission to the outer solar system should return data to confirm the feasibility of the asteroidal impact concept. The plan to move an asteroid to Mars requires the use of a thermonuclear rocket to push it into the correct orbit for impacting the planet’s pole. But the downsides are, of course, the cost for one. Secondly, the time it would take to coast an asteroid into a new orbit. It is estimated that it would take around 10 years of steady maneuvering done by the rocket, followed by 20 years of coasting to impact (Zubrin, et al.).

However, with creating such technology one must remember that it would also give its possessors an unprecedented ability to destroy life on Earth- a potential problem with this idea. The Outer Space Treaty of 1967 banning the use of thermonuclear weapons for planetary engineering. Although rockets are different from missiles, yet another ban stands in the way of using this method. The 1963 Limit Test Ban Treaty also prohibits the explosion of nuclear weapons anywhere except beneath the surface of the Earth (Lewis, 926).

There are many ideas for creating an artificial atmosphere. One entails the use of halocarbons. In 1974, U.S. chemists Mario Molina and Sherwood Rowland predicted that common halocarbon refrigerants, the chlorofluorocarbons (CFCs), would accumulate in the upper atmosphere and destroy protective ozone (Molina, et al.). Within a few years, ozone depletion was being observed above Antarctica, leading to bans on production and use of chlorofluorocarbons in many countries. In 2007, the Intergovernmental Panel on Climate Change (IPCC) said halocarbons were a direct cause of global warming (Solomon et al.).

The idea for employing this method on Mars is that factories producing enough halocarbons could potentially raise the temperature and pressure to a habitable level. The problem, aside from cost, would be that the air produced would still be unbreathable by humans. Creating a greenhouse effect using these chemicals would just add an extra step towards a habitable Mars. This is because we would then need to introduce many hardy plants to create oxygen for us, but would in turn reverse the process of building an atmosphere because the CO2 levels would decrease. This is probably one of the most unlikely scenarios because the cost of building factories and sending technicians to run the factories is unfathomable, not to mention that this plan would take several centuries.

Now we consider scenarios by which Mars is made habitable in a more complete sense for microbes, plants, other animals, and humans. The table below is a guide to what needs to be done to the atmosphere to achieve this goal (Lewis, 924).

One of the most desirable methods proposed for someday inhabiting mars is to create “biome domes” or greenhouse-like structures with an artificial atmosphere, and this idea is what I will be focusing on next. Bio-domes would allow scientists the opportunity to conduct studies on the red planet in order to then plan how they’ll eventually engineer it and make the entirety of it hospitable. Since it has long been accepted that transporting food supplies to future bases on Mars is not economically practical over long periods of time, the cost of sending tons of foodstuffs over vast distances isn’t feasible and that’s why greenhouses would be a good first step to take.

Building greenhouses (“para-terraforming”) on mars requires great feats of engineering and innovation, just as any of the aforementioned techniques. Designs must be able to withstand the harsh Martian environment of low temperatures, high UV radiation, and intense dust storms. Inflatable greenhouse designs have the advantage of being lightweight, manufactured on Earth, and able to expand and inflate on Mars so they don’t take up much space on the launch vehicle. We need to invest in research and development of what designs work before we spend resources on the construction of a prototype. The most practical course of action would be to figure out a way to manufacture these greenhouses on Earth so they can be shipped to Mars for assembly on the surface (Graham, et al.).

The famed Pulitzer Prize winner, Carl Sagan, “A manned expedition to mars would be very desirable,” said Sagan (Hartmann, 161). Top priority is building a dependable greenhouse that can produce the best and most sustainably grown food for the human colonists. Robots are expensive and usually heavy so most of the cultivation and horticulture is ideally to be conducted by one specialist rather than computers. Additionally, computer boards and circuits are likely to have a short lifespan in humid environments such as a greenhouse.

We must plan for exactly how much food must be grown for the number of people being supported. The correct ratio of square meters per person should include estimates for food shortages due to system failure, so there must be a surplus generation of crop. The most likely system failure would be a freezing incident that could wipe out entire crops. Preservation and storage should also be taken into account when planning for colonization (Graham, et al.).

Additionally, the greenhouses must be able to facilitate a large variety of crops as to make sure and have a healthy diet. Not only would it be important to grow fruits and vegetables, but to have a diet full of protein and amino acids it is necessary to grow grains, legumes, and nuts as well. Pollinators will be necessary. Pollinators such as bumblebees are better than honey bees for Martian greenhouses because they adapt more readily to new environments. Pollination is more efficient if humans don’t waste time doing it by hand, so it is necessary to consider how pollination will occur without the aid of wind. A priority is to make the greenhouses dual functioning as a part of a controlled ecological life support system (CELSS) (Graham, et al.). The crops grown will remove carbon dioxide exhaled by the colonists and replace it with oxygen.

Although the technologies are often speculative and the task of terraforming seemingly impossible, who can doubt that if the first steps are taken, the developments required to accomplish the task will eventually become realized. Ultimately, the fate of the citizens of Earth might someday hinge on the colonization of another planet. Even with all of the uncertainties, we have theorized ways to get humans to Mars and sustained merely using early to mid 21st century technology. While our immediate descendants cannot expect to use these methods in the near future, we can hope to one day terraform the red planet making it hospitable to life and in doing so gain knowledge on the evolution of planets and the management of our home planet.

In summary, despite the immense challenges before us, it appears that we could potentially bring Mars to a clement surface temperature that would be suitable for plant life. More complex, though, will be to create conditions on Mars that are suitable for unprotected humans to survive.

"And yet the human spirit is expansive; the urge to colonize new environments lies deep within many of us" – Sagan

Sagan is talking about the colonization of space, not the kind on Earth. Even with the optimistic assumptions about technological advancements and investor interest, it is not yet entirely clear whether the planetary engineering of Mars is within our reach. Especially considering the enormous problems for life still at play here on Earth.

Works Cited

Author unknown. "Climate of Mars." Wikipedia. Wikimedia Foundation, n.d. 11 Feb. 2015. Web.

Fogg, Martyn J. Terraforming: Engineering Planetary Environments. Warrendale, PA, U.S.A.: Society of Automotive Engineers, 1995. Print.

Graham, James M., and Kandis Elliot. "Terraforming Mars: Can We Feed Ourselves If We Go?" AIP Conference Proceedings654.1 (2003): 1292. Academic Search Premier. Web. 11 Mar. 2015.

Hartmann, W. K. "The Cosmic Connection. An Extraterrestrial Perspective by Carl Sagan. Doubleday, New York, 1973. Xiv, 274 Pp., Illus." Science 184.4137 (1974): 663-64. Web.

Lewis, John S., Mildred Shapley. Matthews, Mary L. Guerrieri, James B. Pollack, and Carl Sagan. Resources of Near-Earth Space. Tucson: U of Arizona, 1993. Print.

Mastos, Helen "Astrobiology Magazine Exploring the Solar System and beyond." Astrobiology Magazine, 28 June 2013. Web. 18 Mar. 2015. Web.

Traicoff, Karen. "Welcome to NASA Quest!" Welcome to NASA Quest! NASA, 2011. Web. 18 Mar. 2015.

Zubrin, Robert M., and Christopher P. McKay. "Technological Requirements for Terraforming Mars." Technological Requirements for Terraforming Mars. Pioneer Astronautics and NASA Ames Research Center, 2011. Web. 17 Mar. 2015.

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