Sunita Williams and Barry ‘Butch’ Wilmore only expected to be in space for eight days

Two American astronauts who are currently stranded in space could end up with just 96 hours worth of oxygen in a worst-case scenario, an expert has claimed.

Sunita Williams and Butch Wilmore set off into space on June 5 with the expectation that they’d be back a little over a week later, but more than two months on the two astronauts are still living among the stars.

The pair became stuck when the Boeing Starliner spacecraft which carried them to the International Space Station began to experience technical issues, which meant their return to Earth had to be delayed.

In an update given on 14 August, NASA assured both Williams and Wilmore are ‘doing great’ and keeping busy on board the ISS.

The space agency admitted the two astronauts could be in space for as long as eight months if they have to wait for a SpaceX craft to bring them back, but their return could come sooner if they are able to use the Boeing Starliner.

With discussions about the best way to bring the astronauts back still ongoing, Rudy Ridolfi, a former commander of US military space systems, shared his thoughts on using the Starliner and claimed there are three severe scenarios that could occur in a worst-case situation.

Sunita Williams and Butch Wilmore are said to be ‘doing great’. (NBC News)

Speaking to CNBC TV 18, Ridolfi explained that the safe re-entry of the Starliner relies heavily on the alignment of the spacecraft’s service module. If the alignment is off, there could be three potential outcomes:

96 hours of oxygen

One of the potential scenarios, Ridolfi claimed, is that the Starliner may attempt to reenter the Earth’s atmosphere at an improper angle, causing it to bounce off and remain in orbit.

The craft could them become stranded in space with malfunctioning thrusters, and just 96 hours worth of oxygen on board.

Failure to re-enter the Earth’s atmosphere

A faulty alignment may also put the Starliner at risk of failing to enter the atmosphere altogether, leaving it in space indefinitely.

The astronauts are working on the space station. (Getty Stock Photo)

Vaporisation

Arguably the most dire of the three scenarios, Ridolfi said that if the Starliner were to reenter the atmosphere at too steep an angle, it could cause extreme heat and friction to hit the Starliner’s heat shield.

The severity of the situation could lead the shield to fail, in turn causing the spacecraft to burn up altogether.

As I mentioned, these are worst-case scenarios for the astronauts and if Ridolfi has thought of them, it’s likely that NASA has too.

The agency has said it will make a decision regarding the return of Williams and Wilmore by the end of August.