Experienced astronauts Sunita “Suni” Williams and Commander Barry “Butch” Wilmore arrived at the International Space Station (ISS) in June 2024 thinking it was a routine eight-day stay.
Little did they know they would end up stranded in space for nine months, as the aircraft that brought them there – Boeing’s new Starliner – suffered several technical issues that made it too risky to make the return flight.
They are finally set to head home in the coming days, hitching a ride on a SpaceX aircraft that will land them in Florida.
But why have they been away for so long and what are the effects of such a lengthy stay in space?
How did they get stuck?
Ms Williams and Mr Wilmore blasted off on 5 June in Starliner’s first crewed mission.
The whole point of the mission was to test the spacecraft, which was tipped to be a critical alternative to Space X’s Crew Dragon spacecraft, which is currently the only shuttle for US, European, Canadian and Japanese astronauts to and from the ISS.
They arrived safely, but the space capsule had five helium leaks, five dead manoeuvring thrusters and a propellant valve that failed to close completely.
In the following weeks, Boeing and NASA conducted a series of tests both in space and on the ground, using a Starliner replica, to try and fix the problems the aircraft faced.
Even as late as August, Boeing insisted it was confident the Starliner, which was developed on a reported $5bn NASA contract, could safely bring back the astronauts.
But both NASA and Boeing eventually deemed it too risky, so the Starliner returned to Earth unmanned last September, leaving Ms Williams and Mr Wilmore behind at the ISS.
They are not alone, as NASA astronaut Nick Hague and Russian cosmonaut Alexander Gorbunov joined them at the ISS in September.
