1
Moxley
Sustaining a Martian Atmosphere: Fantasy versus Feasibility
Chris Moxley
Professor Bray
Math of the Universe
15 February 2016
From innumerable science fiction novels to the recent Best Picture Nominee, The Martian, the challenges and opportunities present in the colonization of Mars have consistently captured society’s imagination. Space colonization is no longer just a Sci-Fi fantasy, however, as scientists are beginning to explore the pragmatic possibility of branching out from Earth as an upcoming and attainable frontier. Recent NASA initiatives, such as the rovers Pathfinder, Opportunity, and Curiosity, have begun collecting information pertaining to the soil, atmosphere, water, and overall inhabitability of Earth’s crimson neighbor (NASA, Missions). This is an important area of research because it is possible that space colonization will become an endeavor not of curiosity but of necessity. It is still highly contested in academia what the greatest threat to the human race’s life on Earth is, as it could be climate change, scarcity of energy, disease, natural disaster, or any other calamity. While sifting through that speculation is another topic entirely, the growing fear is that, whatever the true threat is, eventually the human race will have to seek out a new home. For example, popular astronomer Carl Sagan wrote in 1994, “every surviving civilization is obliged to become spacefaring–not because of exploratory or romantic zeal, but for the most practical reason imaginable: staying alive”, and in 2015 physicist Stephen Hawking dramatically added, "We must continue to go into space for the future of humanity.” (qtd. in New Mexico Museum of Space History and qtd. in Griffin). Thus, the topic of a long-term colonization of Mars is both exciting and pertinent. The next step is to understand its feasibility, which heavily depends on the creation of an inhabitable and sustainable atmosphere.
Any permanent inhabitation of a planet most likely requires that the planet’s surface be protected by a thick atmosphere, which Mars lost long ago. An atmosphere provides many life-sustaining functions for its inhabitants, including supplying oxygen, allowing for the development of bodies of water through stable climate control, and absorbing harmful radiation from the sun (Sharp). Scientists believe Mars had such an atmosphere as well as an abundance of water about four billion years ago because a comparative analysis of younger Martian meteorites and older surface rocks reveals that, “the surface rocks come from a more oxygen-rich environment, probably caused by recycling of oxygen materials into the interior”, or a process called subduction, in which “old crust is pushed back down into the interior of the planet”, according to the study’s leading geologist Professor Bernard Wood (Panteleo). Wood claims that the source of this oxygen was likely “the breakdown of water into oxygen plus hydrogen”, but both the oxygen and water supplies were diminished due to chemical reactions with the planet’s surface. (Panteleo) The oxygen was consumed by the oxidation of iron while water was consumed, along with CO2, by a chemical reaction with the igneous rock basalt, which is not an issue on Earth because this loss of water and CO2 is continuously restocked by the products of volcanic activity (Panteleo). The much smaller Red Planet, however, quickly became too cool for volcanic activity, so this process ultimately thinned the atmosphere until it could not retain any more heat and eliminated the possibility for liquid water retention (Panteleo). Though this effect partially explains the loss of oxygen, water, and CO2, it was not alone in stripping away the atmosphere.
The destruction of the Martian atmosphere is further explained by solar winds in the absence of a strong magnetic field. Citing research from NASA’s ongoing MAVEN mission, which studies Mars’ “upper atmosphere, ionosphere, and interactions with solar wind” (NASA, MAVEN), scientists believe that “charged particles from the Sun slam into the Mars upper atmosphere, piling up in a bow shock ahead of the planet. The inner boundary of this bow shock reaches the Mars ionosphere, and can accelerate ions to escape velocities,” essentially stripping the Mars atmosphere bare at an average rate of a quarter pound of gas per second (Shirah). This does not happen to Earth because Earth’s magnetic field peaks at around 65000 nanotesla in strength, which is “more than 40 times stronger than Mars” (Lakdawalla). The presence of Earth’s strong, unified magnetic field is currently explained by dynamo theory, or the process by which the liquid iron of the outer core, heated to convection by gravitational energy in the inner core, conducts an electric current to produce a continuous and double-layered magnetic field (Bettex). The magnetic field of Mars, however, is not only weaker where it exists but does not even cover the whole planet, being almost entirely absent from the northern hemisphere (Lakdawalla). The explanation as to why Mars has such an asymmetric magnetic field is yet another unsettled debate, but the important fact remains that the magnetic field is neither all-encompassing nor strong enough where it exists to repel solar winds and protect Mars from atmospheric erosion. This is then an essential challenge in making Mars inhabitable for a large, permanent colony. Perhaps a few carefully trained individuals could survive for a time in a small, glass-enclosed biosphere underground; however, any attempt to make Mars a livable colony for the masses to prosper in would almost certainly require the engineering of a protected natural atmosphere that could sustain bodies of water and provide radiation absorption, climate control, and oxygen. To protect such an atmosphere, scientists would ideally first create a unified, Earthlike magnetosphere around the planet. While this is an incredibly daunting task with more unknown than known about its feasibility, there exists some indication that the necessary components for the solution are already in place.
Modeling of the Martian core suggests that it could be conducive to creating a magnetosphere, but a great amount of information is still needed to clear up current mysteries. A 2007 lab study led by Andrew Stewart of the Swiss Federal Institute of Technology in Zurich attempted to recreate the conditions found on Mars to determine whether the core was solid or liquid. After they “compressed mixtures of iron, nickel, and sulphur up to the maximum pressure expected in Mars’ core,” the team found that the inner core was most likely liquid and therefore would not develop a magnetosphere through Earth’s method of molten flow around a solid center. (Shiga) However, the scientists found traces of “snow”, or crystalizing iron, closer to the outer core. Stewart finds this to be possible evidence that “convection and heat-flow could change dramatically and this could have knock-on effects on the rest of the planet… such as a new magnetic dynamo being established, or even the start up of surface tectonics”, a promising source for a strong magnetosphere (qtd. in Shiga). While this could take millions of years to naturally occur, it is conceivable that human engineering of the relatively small planet’s core could expedite the process. There is an unfortunate but understandable lack of research to that end, however, because there is still too much unknown about the composition of Mars’ core. For example, if it will in fact crystalize, it is unclear whether the core would best solidify from the outside in or the inside out, “depending on the precise mix of nickel, iron, and sulfur” (Lovett). To elucidate the mysteries, NASA plans to launch the InSight spacecraft, equipped with a seismometer and a heat transfer probe to check the planet’s seismology, core temperature and composition, and other relevant tectonic activity (NASA, InSight). Unfortunately, technical difficulties in the probe’s construction have pushed back its intended March 2016 launch date indefinitely, so it will be a couple years before this mission comes to any scientific fruition (NASA, InSight). In short, it is hard to gauge the possibility of engineering a Martian magnetosphere because not enough is understood about Mars’ core. However, the earliest indications provide hope that the foundation for a magnetic field is in place, and that data from the NASA InSight program alongside the progression of technology will take this from far-fetched to feasible. While creating a magnetosphere remains an area of great uncertainty, the scientific community has generated an array of realistic ideas for the engineering of an atmosphere.
Many theories exist concerning the creation of a Martian atmosphere, but there is not yet a consensus as to the best solution. Some scientists are exploring the possibility of injecting the atmosphere with extremely powerful greenhouse gases that have long lifetimes, such as ammonia. According to SpaceX researcher Margarita Marinova, “the addition of greenhouse gases on Mars would raise the global temperature, which would in turn melt the frozen CO2 polar caps…and with the higher temperature and pressure, liquid water would be stable on the surface of the planet” (Marinova). Ideas proposed to inject these powerful gases into the atmosphere range from the seemingly practical, such as building greenhouse gas factories on the planet’s surface, to the excitingly radical, such as “attaching nuclear, thermal-rocket engines to ammonia-heavy asteroids and redirecting the asteroids” to collide with Mars and release the ammonia into the air (PBS). Still, most agree with Marinova’s assertion that thawing these frozen CO2 deposits will play a critical role in thickening the atmosphere, and some have even more fantastic, yet scientifically possible, proposals to accomplish this goal. Leader of SpaceX, and eccentric thinker Elon Musk went as far as to say that detonating nuclear warheads over the poles could sufficiently heat the planet to a suitable level (Masunaga). While no one is scrambling to give him the launch codes, many agree that the development of mankind’s understanding of fusion could potentially play an important role in terraforming Mars. Others have considered using “orbital mirrors” to intensely reflect visible and infrared sunlight to heat the planet (Grant, Edgington, Rowe-Gurney, and Sandhu). Though a 2011 paper employing global temperature equations concluded that, with today’s technology, “a mirror at Mars’ orbit would not produce energy for a net global change to melt polar ice”, the scientists did find that the idea could be employed to heat up smaller sites, such as frozen lakes (Grant, Edgington, Rowe-Gurney, and Sandhu). Even if not all of these theories will become viable solutions, they indicate that intelligent, motivated, and, perhaps most importantly, well-funded scientists are interested in terraforming Mars. The discussion of terraforming is still in its nascence and will benefit greatly from improvements in technology and the continued study of Mars’ characteristics, so it is a promising sign that there already exists a solid foundation of ideas.
The colonization of Mars will almost certainly start with the initial steps of a few curious individuals following the example of Louis and Clark or Neil Armstrong to simply explore the unknown. Their first orders of business will likely be to survive each day and to study their surroundings as best they can, not to engineer Mars’ core dynamo to create a magnetosphere, nor to thaw the CO2 polar deposits with an influx of ammonia. It is also true thatmore immediate problems, such as maintaining stable food, water, and oxygen supplies under the current atmospheric conditions, will first have to be solved. And yet, it is critical to keep sight of the big picture challenges of establishing a permanent colony, and it is exciting that they are already on the minds of so many scientists. This is because, if Carl Sagan, Stephen Hawking, and many others of the world’s brightest minds are to be believed, the future of the human race is not merely the limited study of other planets, but the extensive exploration and inhabitation of the universe. To this end, creating sustainable life for the masses on Mars would indeed be quite a giant leap for mankind.
Works Cited
Bettex, Morgan. "Explained: Dynamo Theory." MIT News. MIT News Office, 25 Mar. 2010. Web. 15 Feb. 2016.
Grant, M., A. Edgington, N. Rowe-Gurney, and J. Sandhu. "Terraforming Mars-Orbital Mirrors: Operation." Journal of Physics Special Topics 10.1 (2011): n. pag. Physics Special Topics. University of Leicester, 16 Nov. 2011. Web.
Griffin, Andrew. "Stephen Hawking: Humanity Needs to Live in Space or Die Out." The Independent. Independent Digital News and Media, 27 Apr. 2015. Web. 15 Feb. 2016.
Lakdawalla, Emily. "Why Is Only Half of Mars Magnetized?" The Planetary Society. Planetary Society, 24 Oct. 2008. Web. 15 Feb. 2016.
Lovett, Richard. "Mars's Liquid Center Cooling in Unusual Manner, Study Suggests." National Geographic. National Geographic Society, 31 May 2007. Web. 15 Feb. 2016.
Marinova, Margarita. "Margarita Marinova: Turning the Red Planet Green." Interview by Novinite. Novinite. Sofia News Agency, 29 Aug. 2005. Web. 15 Feb. 2016.
Masunaga, Samantha. "What Scientists Say about Elon Musk's Idea to Nuke Mars." Los Angeles Times. Los Angeles Times, 10 Sept. 2015. Web. 15 Feb. 2016.
NASA. "Mars Exploration Current Missions." NASA. Ed. Tony Greicius. NASA, 30 July 2015. Web. 15 Feb. 2016.
NASA. "MAVEN Mission Overview." NASA MAVEN. NASA, 30 July 2015. Web. 15 Feb. 2016.
NASA. "NASA Suspends 2016 Launch of InSight to Mars." InSight. NASA, 22 Dec. 2015. Web. 15 Feb. 2016.
New Mexico Museum of Space History. "International Space Hall of Fame: Carl Sagan." New Mexico Space Museum.New Mexico Department of Cultural Affairs, 2005. Web. 15 Feb. 2016.
Panteleo, Rick. "Mars Once Had Oxygen-Rich Atmosphere." VOA. Broadcasting Board of Governors, 30 July 2013. Web. 15 Feb. 2016.
PBS. "The Mars Prospect." PBS. PBS, 2005. Web. 15 Feb. 2016.
Sharp, Tim. "Earth's Atmosphere: Composition, Climate & Weather." Space.com. Purch, 19 Sept. 2012. Web. 15 Feb. 2016.
Shiga, David. "Lab Study Indicates Mars Has a Molten Core." New Scientist. Reed Business Information, 31 May 2007. Web. 15 Feb. 2016.
Shirah, Greg. "Solar Wind and Mars Bow Shock." Science Visualization Studio. NASA, 5 Nov. 2015. Web. 15 Feb. 2016.