The dream of actually building settlements on other worlds is as old as the space age. While hitherto, all voyages into space have been temporary, the idea of space settlements implies people going to live and work in space for the rest of their lives, much as people hundreds of years ago voyaged to the Americas, leaving their old lives behind, and building new ones in a new continent.

The problem with space settlements in the near term is that there aren’t any places in the solar system where people can live without a technologically advanced life support infrastructure. People proposing to live on, say, the Moon or Mars would have to bring or extract their own oxygen and water, as well as grow food and produce energy. There is no other place in our solar system, besides Earth, where people can live out of doors.

What is Terraforming?

Terraforming is a concept that scientists have envisioned that could bring dead worlds to life, so that people might more easily live on them. Terraforming literally means to “make Earth-like”. The idea is to change the environment of another planet to make it suitable for human habitation using various technological techniques.

Candidates for Terraforming

Four worlds are at about the right size and mass to be candidates for terraforming. These worlds are Venus, Mars, Europa (a moon of Jupiter), and Titan (a moon of Saturn.) But Europa and Titan are too far from the sun and are therefore too cold. Venus is too close to the sun and has an incredibly thick atmosphere, and is therefore too hot, with an average temperature of about 900 degrees Fahrenheit. That leaves Mars.

Why Mars?

At first glance, Mars seems to be a poor candidate for a new world for humanity as well. Its thin atmosphere is almost entirely made up of carbon dioxide. The average surface temperature of Mars is about minus 81 degrees Fahrenheit, with extremes ranging from plus 75 degrees to minus 100 degrees.

There are some characteristics of Mars that make it more Earth-like. It’s rotational rate is almost exactly that of Earth’s, just over twenty four hours. It has a axial tilt of 24 degrees as opposed to that of Earth at 23.5 degrees. While Mars has one third the gravity of Earth and is half again as far from the sun as Earth, it is close enough to experience seasons.

What’s more, Mars has all the elements that are necessary for sustaining life. There is water in the form of ice at the poles and perhaps, according to the findings of NASA probes, underground. The carbon dioxide atmosphere contains both carbon and oxygen. There is also a small amount of nitrogen in the Martian atmosphere.

Based on the discoveries of probes like Spirit and Opportunity, scientists have concluded that Mars was more Earth-like billions of years ago. There was almost certainly a thicker, more oxygen rich atmosphere. There was running water in the form of rivers and even small oceans. There might even have been life of some sort, though signs of that have yet to have been uncovered.

Given these facts, Mars becomes a prime candidate for transformation into a smaller, sister of Earth. It would be the most challenging project in human history, taking several decades or several millennia, depending on whom one asks.

How to Terraform Mars

NASA’s Chris McKay and Mars visionary Robert Zubrin have suggested that there are three possible ways to terraform Mars.

The first is to construct giant mirrors, with diameters in excess of two hundred miles, to focus the sun’s energy on Mars, to cook out frozen carbon dioxide at the Martian poles and in the Martian surface to thicken the Martian atmosphere. The second is to artificially produce a greenhouse effect by building plants on Mars that would produce chlorofluorocarbons or CFCs and release them into the atmosphere. The third and most drastic method is to smash ammonia rich asteroids onto Mars, releasing a great deal of energy, melting trillions of tons of water and raising the temperature of Mars to a livable level in a matter of decades.

Because using mirrors alone might be insufficient to trigger a Martian greenhouse effect and using ammonia rich asteroids would be the equivalent of bombing Mars with 70,000 megaton explosions, McKay and Zubrin conclude that using greenhouse gas producing plants on Mars, perhaps along with mirrors, is the better solution for terraforming.

Bringing Mars to Life

The first stage for terraforming Mars would be to create nuclear powered greenhouse plants that would extract greenhouse gasses from the Martian soil and release it into the atmosphere. McKay and Zubrin believe that this would require a large industrial infrastructure on Mars supported by several thousand people and with a budget of several hundred billion dollars.

As the temperature of Mars rises, the atmosphere thickens, the radiation level on the Martian surface decreases, and water begins to flow, genetically engineered plants can be introduced to begin creating an oxygen rich atmosphere. McKay and Zubrin estimate, given current technology, that this method would produce a Mars upon which people can go outdoors unprotected in about nine hundred years. Long before that time, people could go outside on Mars wearing nothing more complicated than breathing gear.

Greater power sources—say fusion derived—for the greenhouse plants and better engineered plants could compress that time from centuries to decades. Developing such technology in the 21st Century would not be inconceivable, given the history of technological advances just in the past century.

Terraforming in Science Fiction

Terraforming, especially of Mars, has been a familiar subject in science fiction. One of the first instances was in the novel, The Sands of Mars, by Arthur C. Clarke, published over fifty years ago, More recently, Kim Stanley Robinson explored the technological feasibility and the sociological implications of terraforming Mars in his Mars trilogy, which includes Red Mars, Blue Mars, and Green Mars.

A New World for Humanity

If one accepts the most optimistic schedule for terraforming Mars, then it could be that by the end of this century, a “blue Mars”, teeming with life, with breathable air, and free flowing water will be a reality. Such a world could be, for our grandchildren and great grandchildren, a new frontier, much as America was for our ancestors. It could be a place for people to build new lives and experiment with new ways of ordering society. Frontiers test and strengthen the people willing to go to them and make them their home. Finally, building a new world on Mars, and making it a new home for restless people, would help ensure the long time survival of the human species. A multiplanet civilization cannot be destroyed by some cataclysm, either natural or manmade. In an era of great anxiety about the long term prospects of the human race, that is a promise that would be worth a lot to fulfill.

External Links:

• Technical Requirements for Terraforming -
• Terraforming Information Page -