Terraformation

What is terraformation? Well, terraforming a world means transforming it into a living, habitable planet, with a breathable atmosphere and a bearable temperature. It is difficult to talk about specifics beyond that without referring to a planet in particular.

For some time now, Mars has been the subject of much scientific research onto how it could conceivably be terraformed. Mars currently has a mean surface temperature of minus 60ºC and an atmosphere that is only 0.7% the thickness of our own. To terraform Mars, you would have to increase its atmospheric pressure by over 200 times (Mars would require a thicker atmosphere than ours due to its lower gravity) and increase the temperature by at least 60ºC.

		An artist's impression of a terraformed Mars. Courtesy James Graham and Kandis Elliot.

Sounds impossible? Presented with these facts, it certainly seems like an unsurmountable task but many distinguished scientists at NASA have carefully gone through the numbers involved and concluded that the terraformation of Mars is not only achievable but plausible.

We talk more about the details of terraforming Mars in our Mars Case Study.

What about other planets? Well, Mars is very attractive to scientists due to the fact that it is believed to be similar to Earth in many ways. We are almost 100% certain that there are still large quantities of water on Mars due to the fact that we can see evidence of running water from possibly only thousands of years ago (a very short time when you're dealing with geological timescales that can run into billions of years).

Mars also has large deposits of metals and other elements that would be required to sustain life.

The only other terrestrial planet in the solar system apart from Mars that could possibly be terraformed is Venus; Mercury is far too close to the sun and has a mean surface temperature of 179ºC that can rise as high as 427ºC and as low as minus 179ºC.

Venus, on the other hand, is slightly more hospitable - but only just. As opposed to Mars and Mercury, Venus has an extremely thick atmosphere that is 92 times that of ours. Its surface temperature is 482ºC. No scientists have seriously considered the terraformation of Venus simply because the planet is not particularly interesting and it would be almost impossible for humans to land on the surface due to the high temperature and pressure and the constant vulcanism.

		Two volcanoes on Venus are depicted here; Gula Mons (3km high) on the right and Sif Mons (2 km) on the left. Courtesy NASA/JPL.

What's more, a day in Venus is 243 Earth days long - that means that night lasts for approximately 120 days long.

Of course, science fiction has risen to the challenge. Authors such as Kim Stanley Robinson postulate that a huge solar 'parasol' could be placed in between Venus and the Sun, cutting all light off from the planet. Over hundreds of years, the temperature would plummet and the mainly carbon dioxide atmosphere would cool down, then rain and freeze on the surface. Once that was done, the carbon dioxide ice now on the surface could be processed by robots into carbon and oxygen. Finally (and most unbelievably) either the parasol would be opened slightly so that the temperature could be raised so the planet would be habitable and mirrors would be placed in orbit, or the planet would be spun up using magnetic induction so that it would have a shorter 'day'.

It must be noted that no-one really takes these ideas particularly seriously and nearly all space advocates believe that the terraformation of Venus is far more trouble than it is worth when you could build innumerable habitats in space and terraform Mars, and end up using less resources in the process.

Of course, the question must be asked - why should we terraform planets in the first place? And that's a question we answer in the next section; Terraformation Ethics.