Articles - Terraforming Mars
1. Introduction
Mars has long held a special place in the human imagination with countless books and movies telling the story of a colonised Mars with green planes, flowing rivers and clear blue skies. Since 1965, when Mariner 4 successfully beamed back the very first pictures from the red planet, all evidence suggests that Mars is now nothing but a desolate, lifeless planet with little to offer mankind. Being 50% farther from the Sun, Mars' insolation is on average only 43% that of Earth and combined with the absence of a dense atmosphere leads to a mean global surface temperature of ~217K (-56oC) compared to 290K on Earth. The very thin atmosphere that is present is composed mainly of Carbon Dioxide with a little nitrogen, argon and trace amounts of other elements. The small amount of oxygen is believed to have nothing to do with biology and is generated photochemically. There is no earth-like ozone layer for UV protection, the pressure at the surface is only about 7 millibars (mbars), no liquid water is visible anywhere over the entire planet and there is no significant magnetic field, suggesting that the planet's core is either solid or completely liquid [1].
Why therefore would anyone ever want to go to Mars? Is it to answer the life long question of whether we are alone in the universe? Is it to feed our ever growing and inherent sense of adventure? Is it, sadly, due to our incessant need to always be ahead of others? Yes. There is however a reason more vital than any of the above - that of survival. There are at present more than 6 billion people on Earth and the numbers are constantly rising. It will not be long before our planet can no longer sustain such a large population and we will eventually be forced to seek out new homes. Missions to Mars have provided data suggesting that Mars was once a much warmer planet on which water may have flowed and life existed. It is also believed that water may still exist both in the Martian polar caps and the Martian regolith. There are many similarities between the Martian atmosphere that exists today and the Earths atmosphere billions of years ago thus leading us to believe that the red planet has much more to offer us than what meets the eye and that it could one day, possibly in the not so distant future, become our second home.
Colonising a planet such as Mars, where despite the hostile environment, all chemical requirements of life are believed to be present, has the advantage of readily available resources. These, and the presence of a gravity well, render Mars capable of hosting a global, uncontained, biosphere similar to that of the Earth [2-3]. The ultimate strategy in Martian colonisation will therefore be to create a counterpart Earth on Mars. Such a process is known as Terraforming. The word originated in science fiction [4] but was later officially admitted into the English language [5]. It is defined as [3]:
"...a 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."
Making Mars suitable for life and eventual colonisation on a planetary scale inevitably involves large scale changes to its environment and is essentially a two part process; that of ecopoiesis, bringing about changes needed for anaerobic life to be established, and that of full terraforming leading from ecopoiesis to an environment suitable for humans. The term ecopoiesis was first used by Haynes [6] and later defined by Fogg as [3]:
"...the fabrication of an uncontained, anaerobic, biosphere on the surface of a sterile planet. As such, it can represent an end in itself or be the initial stage in a more lengthy process of terraforming."
It is the purpose of this report to briefly look at the principal modifications required for ecopoiesis and terraforming before then going on to consider the various methods for achieving these modifications.