Stephen Hawking says we need to move planet – but is he right?

Hawking explains his doomsday theory in the intriguing two-part BBC2 documentary The Search for a New Earth. It’s a strange and depressing idea. Hawking says that if we continue to confine ourselves to the planet that’s been our home for 200,000 years, we risk annihilation.

“It could be an asteroid hitting the Earth,” he explains. “It could be a new virus, climate change, nuclear war or artificial intelligence gone rogue.” The show poses two simple questions. First, if we are to set up a colony in space, where should it be? Second, how might we do it?

Hawking is joined by Professor Danielle George, an expert in radio frequency engineering at the University of Manchester, who travels round the planet to find out how we might make Hawking’s suggestion a reality. Here, she explains all…

Do we really need to leave earth?

Well, Stephen Hawking thinks we’ll have to, but my view is slightly different. For me, it isn’t “Let’s get off this planet, quick” — it’s more about investigating how amazing it would be if we could become a two-planet species.

What does a new planet need to be human-friendly?

The big challenges are food, oxygen and water. Can we grow crops? But there are other questions, too. Does the new planet have an atmosphere? We’ll need one to shield us from harmful cosmic rays.

How many people will it take to set up a colony?

Human beings reproduce relatively late in life — and produce few offspring — so we think it will probably be around 10,000. But we’d send robots out before people, for sure. There’s no way humans are going to be the first explorers. Robots will try growing crops and then we’ll see what happens.

Stephen Hawking believes Proxima B may be the most suitable planet. Why?

First of all, distance. Proxima B is orbiting one of the closest stars to us, and its orbit puts it in what is known as the “Goldilocks zone”. It’s close to its star, but not too close. Too close, and it will be so hot that water exists as a gas. Too far away, and it’s too cold and all the water freezes.

How far away is Proxima B?

It’s 4.2 light years away. Or, to put it another way, 25 million million miles from Earth.

How long would it take to travel 4.2 light years?

At the speed of our current rockets, around 250,000 years. But in California they are working on a laser technology that can propel things through space at incredible speeds. They are building these “spacecrafts” right now, though at the moment they are only around the size of the SIM card in your mobile phone. But if it all works out, a journey to Proxima B might take just 20 years.

Could we fit 20 years’ worth of astronaut food into a spaceship?

One way around this might be to get humans to hibernate while they’re on board. If you hibernate, you use much less energy and need to consume less food.

Do we have a right to take over another planet?

I don’t think it’s taking over. Humans are curious. This is about seeing what’s out there and finding out if we can live there. If there are already indigenous species we need to do everything to protect them.

Do you think there is the will to make this happen?

I think that is likely to be the biggest stumbling block. At the moment, there isn’t even the money to send people to the Moon. I have no doubt that we can overcome the technological obstacles — we’re a smart race, after all — but I have severe reservations about whether we can overcome the political, financial and ethical issues that stand in the way of us colonising another planet.

The Search for a New Earth is on Monday 9.00pm BBC2