So what about colonisation?
Not surprisingly, getting off Earth multiplies our chances of survival. If we were to plant a self-supporting colony on Mars, say, we would become a two-planet species. This could as much as double our long-term survival prospects. Colonies are also a great bargain.
Send out a few colonists and they can use indigenous materials to sustain themselves and then increase their numbers, as well as seed other colonies elsewhere. The first words spoken on the moon were in English not because England sent astronauts but because it planted a colony in North America that did. A colony on Mars might double our chances of ever going to Alpha Centauri, because 1000 years from now it might be as likely for our descendants on Mars to mount the expedition as for people from Earth to do it.
However, evidence would suggest that you or I are likely to live in a century when the human population is high, at a time in which expensive projects like the space programme are possible. If the population falls catastrophically, expensive projects become more difficult. So it's possible that the human space programme will end before the first colonists blast off, leaving our species on Earth, like passengers stranded on the Titanic without a lifeboat.
Mars is a good place for a self-supporting colony capable of growth because the planet has gravity, solar energy and all the chemicals necessary for life, including water. Locating the colony 10 metres underground would protect it from cosmic rays and solar radiation storms. Even on the surface, the Martian atmosphere offers some protection: I estimate that colonists could explore the surface for up to 31 hours a week and still live for about 70 years.
The first words spoken on the moon were in English not because England sent astronauts but because it planted a colony in North America that did.
As well as offering a good site for a colony, Mars is also very interesting scientifically. If we want to discover whether Mars ever harboured life, having colonists there is one way of finding out.
This colony could start with just eight people. Frozen egg and sperm cells could be used to add genetic diversity. If couples had four children on average, the colony could double in size every 30 years. After 600 years, there could be 8 million people on Mars.
Robert Zubrin, an aerospace engineer and president of the Colorado-based
Mars Society worked out that for every tonne delivered to Mars, you need to launch about 4.9 tonnes into low Earth orbit. To send two craft with eight astronauts to Mars along with two emergency return vehicles - about 100 tonnes in all - would require launching a total of 490 tonnes into low Earth orbit from where they would be sent on a trajectory to Mars.
Gerard O'Neill, a physicist and founder of the
Space Studies Institute in Princeton, New Jersey, calculated that to establish a space colony inside a sealed biosphere, capable of supporting life by recycling air and water, would take at least 50 tonnes of stores per person. Using Zubrin's formula, delivering 400 tonnes of stores to Mars (for eight people) would thus require sending 1960 tonnes into low Earth orbit. Sending the colony and stores, plus emergency return vehicles, would require launching at least 2450 tonnes.
Read page three.
Published on 30 October 2007
