It's pump-it-up day at the International Space Station.

Nasa is releasing air into an inflatable room delivered last month by SpaceX.

If all goes well, the pod will swell four times in volume and demonstrate a new way of living for astronauts. The hour-long process began early on Thursday morning, 250 miles above Earth.

Astronaut Jeffrey Williams opened a valve that allowed air to slowly flow into the inflatable chamber, called Beam (Bigelow Expandable Activity Module).

It is the creation of Bigelow Aerospace, founded by hotel entrepreneur Robert Bigelow.

Nasa paid the North Las Vegas company $17.8 million to test the inflatable-habitat concept at the space station.

Mr Williams and his crewmates will not venture inside Beam - the world's first inflatable room for astronauts - until next week at the earliest.