Trevor Mahlmann
During a press conference on Wednesday, NASA officials publicly addressed for the first time the divisions within the agency over whether the Starliner spacecraft is truly reliable enough to carry two veteran astronauts — Butch Wilmore and Suni Williams — back to Earth from the International Space Station.
The space agency also confirmed key elements that Ars had exclusively reported last week, notably that NASA has been quietly working with SpaceX for weeks on a potential rescue mission for Wilmore and Williams, that the launch of the Crew-9 mission has been delayed until September 24 to account for this possibility, and that Starliner is not capable of autonomously undocking with the vehicle's current software configuration.
NASA's chief of human space operations, former astronaut Ken Bowersox, said no final decisions have been made about how Wilmore and Williams will return to Earth. He said there were reasonable disagreements between engineers at NASA, the customer for the spaceflight, and Boeing, which developed and operates Starliner, about the viability of the 28 reaction control system thrusters used for delicate maneuvers and pointing the vehicle.
“I think it's been very healthy,” Bowersox said of these internal discussions during a call with reporters on Wednesday. “I have to admit, sometimes it's not fun when we disagree. It can be painful to have those discussions, but it's what makes us a good organization.”
NASA has been studying several contingencies, but officials appear to have settled on two different options for bringing the two astronauts back to Earth. They could still fly back on Starliner as NASA engineers become more comfortable with the uncertainties surrounding the booster's performance, and if so, they would do so in the second half of this month or early September. Alternatively, NASA could launch the Crew-9 mission with a complement of two astronauts instead of four, and Wilmore and Williams would join that “increment” on the space station and fly back to Earth in February 2025.
Asked if he thought one of the two scenarios was more likely than the other, Bowersox said he couldn't say. However, a final decision will be made fairly soon. Bowersox said NASA should choose the astronauts' return route by mid-August.
Problems with the thrust
NASA's concern about Starliner's thrusters stems from the failure of five of them during the vehicle's ascent to the space station. Starliner's flight computer disabled five thrusters, supplied by Aerojet Rocketdyne, during the flight. Four of the five thrusters were repaired after overheating.
Since then, Boeing and NASA have been conducting ground- and space-based tests with the small boosters to try to replicate the failure and better understand what fundamentally happens. By identifying the cause, engineers will be confident they can address the problem before Starliner's flight back to Earth.
