Starliner astronauts Williams and Wilmore still in limbo after two months in space

Critical testing prepares Boeing craft for delay-plagued journey from ISS back to Earth

Nasa astronauts Butch Wilmore and Suni Williams await a return to Earth on Starliner after an extended stay aboard the International Space Station. EPA

Nasa astronauts who have spent two months aboard the International Space Station after a series of technical faults with their Boeing Starliner craft prolonged their week-long mission still do not know when they will return to Earth.

Suni Williams and Butch Wilmore arrived on the ISS on June 6 for the first crewed flight of Boeing's commercial space programme.

Starliner has suffered a series of helium leaks and thruster problems since docking, with a firm date for the return journey still to be set by Boeing and Nasa.

The litany of problems sparked concern that the two travellers were stuck in space – but mission chiefs have sought to offer assurances they were well prepared for a lengthy voyage.

Boeing stressed last week it “remains confident” that its craft will be able to transport them home safely.

Nasa said critical tests being carried out to ensure the craft is ready for the flight will continue this week.

“Nasa and Boeing teams continue analysing data from recent ground and spacecraft testing as they evaluate the Starliner spacecraft’s propulsion system,” the American space agency said on its online blog.

“Teams are taking their time to analyse the results of recent docked hot-fire testing, finalise flight rationale for the spacecraft’s integrated propulsion system, and confirm system reliability ahead of Starliner’s return to Earth from the International Space Station.

“Meanwhile, Starliner ground and mission support teams are continuing to prepare for undocking by participating in integrated simulations with space station operations teams.”

Nasa said more information is expected to be shared on the completion of return planning, which is expected to continue this week.

“As always, astronaut safety remains the top priority for both Nasa and Boeing,” Nasa said.

Boeing had hoped a successful test flight which bolster its reputation after safety concerns with commercial flight operations.

It has a $4.2 billion contract under Nasa's Commercial Crew Programme to help safely launch and bring back astronauts for the agency.

However, the development of Starliner has been plagued with delays because of technical problems over the past decade.

“Boeing remains confident in the Starliner spacecraft and its ability to return safely with crew,” Boeing said in a statement issued last week.

“We continue to support Nasa’s requests for additional testing, data, analysis and reviews to affirm the spacecraft’s safe undocking and landing capabilities.

“Our confidence is based on this abundance of valuable testing from Boeing and Nasa. The testing has confirmed 27 of 28 RCS thrusters are healthy and back to full operational capability. Starliner’s propulsion system also maintains redundancy and the helium levels remain stable.”

Space X to the rescue?

Space chiefs may face further complications in their efforts to get the Starliner return mission moving.

A Crew-9 mission to the ISS, carrying three Nasa astronauts and a Russian cosmonaut on a Space X Dragon craft is scheduled to take-off no earlier than August 18.

It is expected to dock with the port occupied by the Starliner, underlining the need for the Boeing craft to lift-off.

It has been suggested that alternative options to bring the Nasa astronauts home may have to be considered, including hitching a ride on a Space X capsule.

Ms Williams and Mr Wilmore are supporting daily duties on the orbiting laboratory while they await news.

Ms Williams, a retired Navy captain, had logged 322 days in space before this mission and completed seven spacewalks totalling 50 hours and 40 minutes.

Mr Wilmore is a US Navy captain who had spent a total of 178 days in space. He was first selected as an astronaut in 2000.