This post was originally published on blogspot.com on October 22, 2011
Terraforming is a recurring idea in both science fiction and real proposals for space colonization. In the latter it is often seen as a logical next step after initial settlements on other planets. Actually there are in space colonization theory two different approaches: 1. colonization of celestial bodies (moons, planets and so on) and 2. using space habitats (free-floating space stations intended for permanent settlements).
Terraforming is, of course, part of the first approach. For some reason approach 1 is the most dominant and best known version of space colonization in both science fiction and public knowledge. We of Republic of Lagrange are, however, supporters of approach 2, which we’ll discuss in an other post.
Terraforming is seen by some planetary chauvinists as the ultimate goal of space colonization. But we want to discuss some issues related to terraforming.
The most important problem of terraforming is the rather small amount of planets or other bodies in our solar system which can be terraformed. Actually only two bodies can be terraformed: Venus and Mars. All other proposed candidates for terraforming have too less mass, to maintain an atmosphere. Although the scientific study of terraforming started with Venus, most likely candidate for terraforming is Mars.
A problem with Mars, and to a lesser degree also with Venus, is that Mars is a lot smaller than Earth. Therefore Mars’ total surface area equals Earth’s total dry land area. Calculations show that if Mars is changed into a blue planet approximately half of its surface will be covered with a two kilometer deep ocean, and so reducing the potential area for settlements. If we use Earth’s current population density, this gave living space for some three billion people, that sounds a lot (and it is), but if future space civilization grows to a multiple tens of billions people, the combined surface area of Earth and Mars, whether or not terraformed, is much too less.
The same problem also goes up for Venus, although this planet has some ninety percent of Earth’s total surface area (both land and water). But in order to remove the thick and carbon-dioxide rich atmosphere, some propose to introduce large amounts of hydrogen into the Venusian atmosphere where it should react with CO2 to water and oxygen. However this would cause a Venusian ocean which covers eighty percent of the planet’s surface, with a depth of some hundred meters. A quick calculation the remaining surface will provide Lebensraum for some 4.7 billion people (assuming current terrestrial population density).
Our preliminary conclusion has to be that terraforming only offers a limited amount of land for space colonists. We have to terraform both planets in order to allow a doubling of Earth’s population (at current density).
But is far from the only problem of terraforming, in both cases the total costs will be enormous, Mars will probably be cheaper than Venus, since the former is easier to terraform. And in both cases it will take centuries before the process is completed.
So the question is whether we should go for terraforming Mars and Venus? Honestly, I think we shouldn’t. In each case we need to move vast amounts of resources through the solar system. We could make better use of those materials than for wasting them in terraforming. Free space habitats are cheaper, faster to realize and easier to move. And resources in the solar system allow space habitats to increase mankind’s living space with a factor thousand.