The collective space vision of all the world’s countries at the moment seems to be Mars, Mars, Mars. The U.S. has two operational rovers on the planet; a NASA probe called MAVEN and an Indian Mars orbiter will both arrive in Mars orbit later this month; and European, Chinese and additional NASA missions are in the works. Meanwhile Mars One is in the process of selecting candidates for the first-ever Martian colony, and NASA’s heavy launch vehicle is being developed specifically to launch human missions into deep space, with Mars as one of the prime potential destinations.
But is the Red Planet really the best target for a human colony, or should we look somewhere else? Should we pick a world closer to Earth, namely the moon? Or a world with a surface gravity close to Earth’s, namely Venus?
To explore this issue, let’s be clear about why we’d want an off-world colony in the first place. It’s not because it would be cool to have people on multiple worlds (although it would). It’s not because Earth is becoming overpopulated with humans (although it is). It’s because off-world colonies would improve the chances of human civilization surviving in the event of a planetary disaster on Earth. Examining things from this perspective, let’s consider what an off-world colony would need, and see how those requirements mesh with different locations.
Creating a Mars Colony
First, let’s take a look at what the mooted Mars settlement schemes are offering. The Red Planet has an atmosphere containing carbon dioxide, which can be converted into fuel while also supporting plants that can make food and oxygen. These features could allow Martian colonists to be self-sufficient. They could live in pressurized habitats underground most of the time, to protect against space radiation, and grow food within pressurized domes at the planet’s surface.
Over decades, continued expansion in that vein could achieve something called paraterraforming. This means creation of an Earthlike environment on the Mars surface that could include not only farms but also parks, forests, and lakes, all enclosed to maintain adequate air pressure. (The natural Martian atmosphere exerts a pressure of only 7 millibars at the planet’s surface – equivalent to being at an altitude of 21 miles on Earth!)
For the rest of the story: http://blogs.discovermagazine.com/crux/2014/09/08/where-build-off-world-colonies/#.VA5DcmOOoui