What's going to happen to the ISS?

Chris Smith put this question to Cambridge University space scientist Xander Byrne...

Xander - The reason that they're doing it is because it's getting on a bit. It's been up there, various parts have been there since the mid nineties. Certain modules that are going in are sort of degrading over time. Bits of it don't work as well as they used to. There are sometimes problems with the modules on the station. These are usually fixed by the astronauts there, but the problems are getting more frequent and more difficult and expensive to repair. The ISS itself is, by some estimates, the most expensive thing full stop. Estimated between 100-200 billion dollars. So they're really keen to cut down on that, obviously.

Chris - We also spoke on the programme last week about the fact that this is becoming a commercial initiative. We had the report on the project involving Elon Musk's company, and one other collaborator, to put commercial space stations up there starting in just two years time. And the fact they're making space a commercial domain rather than an international collaborative scientific domain, they'll still do those things, but it's very much something that they think that they can get it paid for by people buying tickets and they're so confident they've already sold tickets at $350,000 a pop.

Xander - And that's exactly why it works. There are always going to be people with this amount of money to throw away, for a very, very short trip into space.