Sunday, August 17, 2008

Colonizing Mars

Earth is in danger. Constantly threatened by impacts with large meteors or blasts of powerful radiation, our planet might one day encounter cosmic forces which could make all of human civilization extinct. We could go the way of the dinosaurs at any time.
For this reason, it would be beneficial to colonize another planet, so that if life here is wiped out, our species will survive. And if a giant meteor does head our way, it would be nice if we had someplace to flee.

Mercury and Venus are far too hot to consider colonizing, and the outer gas giants have no solid surface on which humans could live. Our best bet for a vacation home is our nearest neighbor, Mars. It's about half of Earth's size, has days which last 24.6 hours, and there's considerable evidence that it used to have liquid rivers and seas on its now dry and frozen surface. Probes have detected the presence of methane gas, which could support oxygen-producing bacteria.

Mars and Earth revolve around the Sun at different speeds, which means the distance between the two planets changes. At its closest, it is "only" about 35 million miles from home, which might be traveled in a fast moving spacecraft in three months.

There have been several unmanned explorers on Mars in the past few years, scouting for a good landing site and further evidence that colonizing the planet is possible. Solar powered rovers Spirit and Oppurtunity arrived in June, 2004, and showed conclusively that there was once liquid water on the planet. Phoenix arrived in May of this year, and is searching for evidence of organic material, evidence that life existed there millions of years ago, or that it might support life today.

There are significant barriers to success. The red planet has a very thin atmosphere, which means it's constantly bombarded with powerful UV radiation. Its mean surface temperature is -63oC (-81oF), and the air is 95% carbon dioxide.

To establish permanent habitations, Mars would eventually need to be terraformed. Terraforming is the process of transforming a planet to make it more hospitable to humans. Water frozen in the ice caps could be melted for human use, and energy could be harvested from the still volcanically active interior. Producing greenhouse gases would warm the surface, just like global warming here on Earth, but in a good way.

Nothing like it has ever been attempted before, but NASA and ESA are hoping to launch the first humans within 20 years. Terraforming would take centuries, but the first Martian colonists may arrive within our lifetime.

One theory says we should set up a permanent base on the Moon first. It's weaker gravity would make it easier to launch high speed shuttles for the remaining distance; and although it's been established that the Moon is completely inhospitable to life, it could serve as a way station, as Iceland and Greenland did to Vikings crossing the Atlantic to the New World.
Dissenters say this isn't necessary: Mars is a much better place to establish our first extraterrestrial colony.

NASA is launching its Mars Smart Probe in 2009, looking for a good first location in the Martian Temperate Zone. Thousands have already volunteered for the first manned mission.

For my previous posts on outer space, click here.

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