NASA: SpaceX or Boeing Starliner could bring stranded astronauts home, but they might be stuck until 2025

NASA is looking into Plan B after two astronauts became stranded in space in June.

Astronaut Sunita “Suni” Williams and Barry “Butch” Wilmore, both veteran NASA astronauts and former US Navy test pilots, were launched aboard Boeing’s Starliner from Florida on June 5.

They docked the next day at the ISS, where they were scheduled to spend eight days.

However, a series of issues with Starliner’s propulsion system has extended their mission indefinitely.

NASA is still investigating multiple rescue options to bring the stranded astronauts home, but some options leave Ms Williams and Mr Wilmore stuck in space until 2025.

“Roughly by mid-August, we need to decide” on the Starliner return plan, NASA Commercial Crew program manager Steve Stich said during a press conference.

The deadline for the agency’s decision is driven by the timing of the next crew launch. NASA on Tuesday delayed the launch of SpaceX’s Crew-9 mission by a month, to September 24, in order to buy itself more time to figure out the Starliner situation.

“I don’t think we’re too far away from making that call,” NASA Associate Administrator Ken Bowersox said during the conference.

Three return options

NASA has been preparing a trio of possible plans for returning Wilmore and Williams.

The first is to return the pair on board Starliner and launch SpaceX’s Crew-9 mission with its planned quartet.

The second is to fly the Starliner back empty and remove two astronauts from the Crew-9 mission.

That mission, already scheduled for a typical six-month stint at the ISS, would fly back as planned in February 2025 with Ms Wilmore and Mr Williams onboard.

NASA declined to specify which two astronauts would be taken off the Crew-9 flight.

The third option would be to return Starliner empty and stick with launching four people on the Crew-9 mission.

That would mean Wilmore and Williams would split up for the return, with one coming back with the Crew-8 mission after Crew-9 launches, and the other with Crew-9 when it returns in February 2025.

That option would represent the first time SpaceX would fly five passengers on its Dragon spacecraft.

Boeing continues to make its case to NASA that Starliner is safe, with the company going so far as to make public appeals about the amount of thruster testing that’s been done.

But NASA remains unconvinced, given the inconclusive results of the testing thus far, and the agency’s debates are expected to continue into the days ahead.

If the agency board that oversees the Commercial Crew program can’t come to a consensus, the decision may eventually be elevated to NASA’s chief, Administrator Bill Nelson.

- With CNBC