WASHINGTON — Boeing’s CST-100 Starliner will depart from the International Space Station Sept. 6, ending a three-month flight that saw the spacecraft unable to demonstrate its ability to safely return astronauts from orbit.
NASA announced Aug. 29 that the agency and Boeing completed a readiness review for the upcoming uncrewed departure of Starliner. That review confirmed plans for bringing the spacecraft back to Earth from the ISS.
Those plans call for Starliner to undock from the station at 6:04 p.m. Eastern Sept. 6. It will move away from the station and then perform a deorbit burn, setting up a landing at White Sands Space Harbor in New Mexico at 12:03 a.m. Eastern Sept. 7, or six hours after undocking.
NASA officials had previously identified Sept. 6 as a potential departure date for Starliner. An ISS trajectory file posted earlier this week included both the Sept. 6 date and time for Starliner’s departure.
If NASA and Boeing hold to that schedule, Starliner will undock exactly three months after arriving at the ISS on the Crew Flight Test (CFT) mission with NASA astronauts Butch Wilmore and Suni Williams on board. While the docking was successful, the spacecraft suffered additional helium leaks after launch the day before as well as problems with five reaction control system thrusters.
Starliner was to remain at the ISS for as little as eight days before returning to Earth with Williams and Wilmore on board. However, NASA repeatedly extended the spacecraft’s stay as engineers focused on the thruster problems. The agency decided Aug. 24 to return Starliner uncrewed, concluding uncertainty about how those thrusters would perform during critical maneuvers made it too risky to have astronauts on board.
Starliner will perform a fully autonomous return, NASA said, although ground controllers will have the ability to intervene and remotely command the spacecraft is needed.
“There’s a few things that we have to do differently,” said Steve Stich, NASA commercial crew program manager, about the uncrewed departure of Starliner at the Aug. 24 briefing where they announced Starliner would return uncrewed. That includes having Starliner depart the vicinity of the station faster than planned.
NASA officials said at that briefing that they would wait until after landing to determine next steps for the program, including whether the agency would formally categorize it as a failure.
“We’ve accomplished a lot on this mission and learned a lot about this vehicle,” said Jim Free, NASA associate administrator. “We’ll look at this as we do any of our missions to see if does it fall into any of the categories that we have that we define as a mishap once we get the vehicle back.”
“We need to get the vehicle back. We need to work through our sequence of events on what changes we’ll make both for the helium leaks and the thrusters, and then we’ll make a decision on the next flight,” Stich said.
Starliner’s departure will free up a docking port on the station for the next crew rotation mission, Crew-9, launching as soon as Sept. 24 on a SpaceX Crew Dragon. That mission was to send four people — NASA astronauts Zena Cardman, Nick Hague and Stephanie Wilson and Roscosmos cosmonaut Alexsandr Gorbunov — to the station.
NASA now plans to fly only two people on Crew-9, though, freeing up seats that Wilmore and Williams will use for their return to Earth when Crew-9 ends in February 2025. NASA has not announced which of the original four members of Crew-9 will be retained.
Boeing has not commented on Starliner’s return or other aspects of the commercial crew program since the NASA decision, beyond a brief statement Aug. 24. “Boeing continues to focus, first and foremost, on the safety of the crew and spacecraft. We are executing the mission as determined by NASA, and we are preparing the spacecraft for a safe and successful uncrewed return.”
The last update on a Boeing website intended for updates on the Starliner program was posted Aug. 2, when the company stated it “remains confident in the Starliner spacecraft and its ability to return safely with crew.”
