When are we moving to Mars?

With wars raging and environmental collapse on the horizon, the idea of escaping to start again on another planet is gaining appeal. Both NASA and the Chinese are working on lunar bases. But how soon before the rest of us can take to the stars? And what about the planet we'd leave behind?

- DR KELLY WEINERSMITH

The idea of a mass human migration to space, the Moon or other planets is exciting, but... well, a little overzealous. As the authors of A City on Mars say: "An Earth with climate change and nuclear war and zombies and werewolves is still a better place than Mars." To find out why, we spoke to one of its authors, Dr Kelly Weinersmith, who, after years of research into space settlements, gave us the low-down on how long it's really likely to be before humans can move beyond Earth.

WHY MIGHT IT NOT BE THE RIGHT TIME TO MOVE TO MARS?

There's so much that we don't know yet. In particular, settlements require that people can have babies and we don't have anywhere near enough science to know if that's going to be safe for the mothers or for the babies.

When you move out to a place like Mars where you only have 40 per cent of Earth's gravity and you're completely exposed to space radiation, everything gets harder. We've done a lot of research on the International Space Station (ISS), which has been within the protection of the magnetosphere that surrounds Earth and shuttles space radiation to the poles.

Most of that radiation hasn't hit our astronauts, so we don't understand what it does to human bodies.

There's also a lack of clarity about what you're allowed to do with the resources in space. In 1967, the UN passed the Outer Space Treaty, which says that no one is allowed to claim sovereignty. The US interpretation of this is that you can extract and sell resources from space without claiming sovereignty. But not all nations agree with this.