Sunita Williams in space: What if Boeing’s Starliner spacecraft’s return to Earth is further delayed? NASA says...

The Boeing's Starliner spacecraft, which carried NASA astronauts Sunita Williams and Butch Wilmore to the International Space Station (ISS) on June 5, is all set to return uncrewed to Earth on Friday, September 6.

A few minutes before the Starliner undocks from the ISS, NASA will conduct a “go/no-go” poll to gauge the conditions at the designated landing site in White Sands, New Mexico. Once cleared, undocking is expected at 6:04 pm EDT (3:30 am IST), with springs instantly pushing the spacecraft away from the ISS.

But what if the Starliner's return to Earth is delayed on Friday?

Anthony Vareha, flight director, International Space Station, said on Wednesday that if the joint team, for some reason, decides not to undock on Friday, “we have undocking opportunities on several later days, all of which are subject to weather constraints.”

He added that once the hatch in the Starliner is closed on Thursday, “we will leave it closed, no matter the undocking date.” 

According to a report, backup opportunities are spaced four days apart, providing flexibility to ensure safe touchdown conditions.

Worst-case scenario: 'A very long rule'

While NASA experts said they have full confidence in Starliner and its safe return to Earth, Vareha said, "We have guidance in these rules to say which types of things we can live without versus which things we would actually stop the undocking for; it's a very long rule."

When asked about the worst-case scenario in which the undocking could be delayed, Vareha said on Wednesday NASA expects thrusters of the Starliner to work for the breakout burn. He explained that not just the Starliner but several other factors are taken into consideration during the "go/no-go" poll.

“We are looking at a "go/no-go" poll ahead of the undock. It's not just the Starliner, we go to make sure that the entire ISS and all of its systems are in a good state to support the backing away of the Starliner, ensuring we have good communication between the ground teams, the ISS, the Starliner...all of these things we have to make sure are good to go," the NASA official said.

During its flight to the ISS, the Starliner capsule suffered multiple thruster failures and propulsion-system helium leaks. Boeing conducted extensive thruster tests in space and on the ground and contended the capsule could safely bring the astronauts back. But NASA disagreed, setting the complex ride swap in motion.

Sunita Williams and Butch Wilmore should have returned to Earth on Boeing’s troubled Starliner capsule back in June, a week after blasting off on its first test flight with a crew. 

However, after extensive tests and analysis of thruster problems and helium leaks, NASA decided last weekend that it would be safer for SpaceX to fly them home. But that won’t happen until February 2025, more than eight months after they blasted off.