The CST-100 Starliner spacecraft saga doesn’t seem close to resolution. In fact, it is taking on increasingly unexpected twists that were quite unimaginable not too long ago.
In a briefing on August 7th, NASA confirmed several rumors and behind-the-scenes reports that had been growing stronger in recent days, suggesting that the Agency is seriously considering relying on SpaceX to bring back the two astronauts currently still aboard the International Space Station (ISS).
Launched on June 6, the Starliner Crew Flight Test mission carried to the ISS the two NASA astronauts Butch Wilmore and Suni Williams. The first crewed mission of Boeing’s spacecraft aims to test the CST-100 before starting official flights under NASA’s Commercial Crew Program. The two astronauts were originally supposed to stay in low Earth orbit for only eight days. However, they might now have to remain there for eight months.
The problems began shortly after the launch from the Kennedy Space Center. During the rendezvous maneuvers with the space station, five of Starliner’s reaction control system (RCS) thrusters failed. Four were later restored after overheating.
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Multiple issues, little communications
In the following weeks, NASA and Boeing engaged in extensive discussions and conducted ground tests to identify and resolve the issue before the capsule’s return. These thrusters are indeed essential for both maneuvering away from the ISS and for the re-entry into Earth’s atmosphere.
Until July, NASA and Boeing seemed confident that they could ensure a safe return for Starliner despite the various delays. Recently, however, a shift in communication suggested that the situation was likely more critical than previously reported. For several weeks, NASA provided little to no updates on the situation, while Boeing, in a statement on August 2nd, remained optimistic about the safe return of the spacecraft “Calypso”.
During the briefing on Wednesday, Steve Stich unveiled important details about the tests conducted and publicly confirmed conflicting positions within the agency regarding the return of Wilmore and Williams.
The tests conducted at NASA’s White Sand Test Facility unveiled that the issues could have been caused by the expansion of a Teflon seal in an oxidizer valve. However, the causes of this problem and its potential impact during thruster ignition in Starliner’s maneuvers remain unclear.
“The testing at White Sands and the discovery that the poppet Teflon was extruding after the testing was a bit of a surprise to us. […] That, I would say, upped the level of discomfort.”
— Steve Stich, manager of NASA’s Commercial Crew Program
Additionally, it should be noted that an uncrewed return of the CTS-100 would require an update to the spacecraft’s software package, as it currently cannot perform undocking maneuvers autonomously. This issue was first reported by Eric Berger for Ars Technica and subsequently confirmed during NASA briefing.
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SpaceX steps in
While Boeing continues to push for a crewed return, NASA is demanding additional guarantees. Consequently, further tests are being conducted. A decision must be made by mid-August, with two main scenarios possible: either the return of the two astronauts aboard Starliner or the provision of two seats by SpaceX on a Crew Dragon capsule.
To address this possibility and buy some time, NASA announced on Tuesday the postponement of SpaceX’s Crew-9 mission. The launch is now scheduled no earlier than September 24.
In that case, Crew-9 would liftoff with two people on board instead of four. Thus, Butch Wilmore and Suni Williams would then return at the end of this mission, in early 2025. Way later than the originally planned brief mission.
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