When two American astronauts blasted off on a test mission to the International Space Station on 5 June, they were expecting to be back home in a matter of days.

But things didn't quite go to plan.

In fact, Barry “Butch” Wilmore and Sunita Williams are still there, floating high above the Earth nearly two months later.

The pair - who are stuck indefinitely - now face the sudden prospect of missing the summer entirely and even spending Christmas and New Year in space.

Mr Wilmore, 61, and Ms Williams, 58, flew a Boeing Starliner spacecraft to the station. It was the first flight of its kind with people on board and was a test designed to see how the new spacecraft performs before it is used more regularly.

Problems, however, emerged as it made its approach. These included leaks in its propulsion system and some of its thrusters shutting down.

So while they made it to the space station safely, they will need an alternative mode of transport to get home if the Starliner is not deemed safe to return to earth.

At a news briefing on Wednesday, Nasa officials said no firm decisions had been made when it comes to next steps.

"Our prime option is to return Butch and Suni on Starliner," Steve Stich, manager of Nasa's Commercial Crew Program, said. "However, we have done the requisite planning to make sure we have other options open.”