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The decision to return Starliner home without astronauts on Friday (September 7) was not without controversy, NASA said of discussions with Boeing.
The original plan was to fly NASA astronauts Butch Wilmore and Suni Williams up to and from the International Space Station on Starliner. However, persistent propulsion problems with Starliner could not be resolved to a degree that would meet NASA’s risk requirements. Astronauts Butch Wilmore and Suni Williams will remain on ISS for extended periods in the space station and return home with the SpaceX Crew-9 mission in February 2025.
“I would say, anytime […] where there’s a decision like this, there’s some tension in the room,” NASA’s Steve Stich, program manager for the commercial crew, said of the meeting to return Starliner without astronauts. 4).
“Boeing believed in the model they created to predict thruster degradation for the rest of the flight,” Stich said. “The NASA team looked at the model and saw some limitation. It really had to do with it, do we trust the thrusters, and how much could we predict their degradation from undock through the burn deorbit?”
The spacecraft is scheduled to depart the ISS without its crew on September 6 to return to Earth on September 7, to complete a mission odyssey that began on June 5 after sending its first astronauts into space. It was supposed to be a 10-day mission, although there was flexibility since the mission was developed.
Starliner’s historic first test mission with astronauts to the ISS on June 6 ran into problems after five thrusters (out of 28) in its reaction control system misbehaved. Months of space testing, ground testing and modeling followed, but the root cause — overheating of the fuses, possibly caused by blown insulation blocking drive lines — could not be identified. affirm firmly.
NASA ultimately decided that it was too much of a risk to put the two NASA astronauts back aboard Starliner, and changed its ISS demonstration to bring the astronauts home another way.
Related: The 1st Boeing Starliner crew to return to Earth without astronauts on September 6
“From the point of view of Boeing, they certainly know their spacecraft, and they are analyzing risks and what they think is the potential of the vehicle alone,” said Stich. But he noted that Boeing “isn’t capable” of the same risk trades that NASA does, which he said is an unfair position to put them in given the decision to bring in other spacecraft (SpaceX’s Crew Dragon.)
“You also have to recognize that the agency is in a different position in terms of our understanding of the risks, and what is available to us without Starliner, so the opinions differ as well,” Stich admitted.
Boeing’s commercial crew manager, Mark Nappi, was on the call but did not comment on the meeting Stich was talking about. Boeing’s statement on the flight readiness review last week noted that teams at Boeing “continue to focus, first and foremost, on the safety of the crew and the spacecraft.”
“We are completing the mission as determined by NASA, and we are preparing the spacecraft for a safe and successful unmanned return,” Boeing officials added on X, previously Twitter, on August 24.
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To make room for two Starliner astronauts, Crew-9 was tasked with sending only two astronauts on Crew Dragon instead of the planned four.
NASA astronaut and Space Force Guardian Nick Hague was promoted from Crew-9 pilot to commander, flying into space alongside Roscosmos cosmonaut and mission specialist Aleksandr Gorbunov; Gorbunov’s seat is part of a larger series of interagency seat swaps that are difficult to reschedule. The other two Crew-9 members, NASA astronauts Zena Cardman and Stephanie Williams, will sit out this mission and will be eligible for future assignments.
As for Starliner, after taking off from the solo ISS, it will likely be tasked with making a few “hot fires” as it rapidly retreats from the orbital complex, as part of the ongoing testing of the propulsion system to see what is possible with engineers. learn. (This is especially important since the service module, which contains the thrusters and the affected fuel, is separate from the spacecraft and will burn up in the Earth’s atmosphere.)
“We will do a slightly modified exit after the disconnect,” ISS program manager Dana Weigel said during the teleconference. “Shortly after that, the order will be sent to make a separate stream that will take Starliner up, back and forth behind the station. which is capable and confirmed.
