Nasa pushes back deadline to return Boeing Starliner crew due to safety concerns

Voyage was supposed to last eight days, but technical issues left two astronauts stranded

Suni Williams and Butch Wilmore have been on the ISS for more than two months. AFP

Nasa has pushed back the deadline for the Boeing Starliner's return flight amid concerns over the spaceship's flight readiness, saying the two astronauts stranded on the International Space Station could be there for eight months.

“Right now, the agency has taken the time to ensure we are not putting the crew at a higher risk than is necessary, and as astronauts, that's always something worth waiting for,” said Joe Acaba, chief of the Astronaut Office.

A decision will be made on the matter at the end of the August, Nasa officials said.

Suni Williams and Butch Wilmore have been on the ISS for more than two months, arriving on the first crewed flight in Boeing's commercial space programme, which was supposed to last eight days.

The astronauts were left stranded due to technical problems including helium leaks and thruster issues. Mr Acaba said Ms Williams and Mr Wilmore could be stuck on the ISS for up to eight months, as they would have to wait for a SpaceX Dragon capsule.

The extended time in space could have harmful effects for the astronauts, including increased levels of radiation. And if they do need to return home on a SpaceX flight, they will be doing so without suits, as their Boeing suits are not fit for use.

“This mission was a test flight … they knew this mission might not be perfect,” Mr Acaba said. “Human space flight is inherently risky and, as astronauts, we accept that as part of the job.”

While they wait for a ride home, the two astronauts are keeping busy, officials said, contributing to on-board research and maintenance.

A resupply vehicle is expected to dock at the ISS at the weekend. Nasa is working with Boeing to come up with a solution that will bring the astronauts home.

“I've got tremendous respect for Boeing and the Boeing team and that respect has grown through this process,” Nasa associate administrator Ken Bowersox said.

“We've had very honest discussions with each other and I'm not surprised that the Boeing team is 100 per cent behind their vehicle.”

Boeing remains “confident” in the Starliner's ability to return safely with crew, the company said this month.