NASA and Boeing managers decided again to extend the Starliner crew capsule's stay at the International Space Station, postponing the June 26 re-entry to allow more time for analysis and testing to make sure helium leaks and thruster failures are fully understood, officials said Friday night.
NASA plans to conduct a formal review of reentry readiness before setting a new target landing date. Given the ongoing analysis, Starliner's undocking and return to Earth will likely bypass two spacewalks already planned at the space station on Monday and July 2.
Meanwhile, Starliner commander Barry “Butch” Wilmore and co-pilot Sunita Williams are still authorized to undock and fly home at any time if a station malfunction or other issue arises that requires a quick departure. Therefore, officials say they are not stranded in space.
“We are taking our time and following the standard process of our mission management team,” Steve Stich, director of NASA's Commercial Crew Program, said in a statement. “We are letting the data drive our decision making regarding management of the small helium system leaks and propellant performance we observed during rendezvous and docking.”
Additionally, he said, given the extended duration of the Starliner mission “it is appropriate that we complete an agency-level review, similar to that done prior to the return of NASA's SpaceX Demo-2 after two months in orbit, to document the agency's formal acceptance to proceed as planned.”
He was referring to the first flight of astronauts aboard SpaceX's Crew Dragon ferry in 2020. But the Demo-2 mission did not experience problems like those seen so far on the Starliner's first piloted test flight.
The problem for Starliner troubleshooters is that the helium leak and propellants in question are located in Starliner's drum-shaped service module, which is attached to the base of the crew capsule. The service module is discarded before reentry and burns up in the atmosphere.
Since engineers won't be able to examine the actual hardware after the fact, NASA and Boeing managers want to give them as much time as possible to review telemetry, continue testing and hone contingency scenarios in case additional problems arise after undocking.
They also want to learn as much as possible about what might be necessary to avoid similar problems on subsequent flights. NASA managers had hoped to certify the Starliner for operational crew rotation flights to the ISS early next year, but it remains unclear whether that remains a realistic goal.
In any case, Stich said the Starliner “is performing well in orbit while docked with the space station.”
“We are strategically using the additional time to clear the way for some critical station activities while we complete preparation for the return of Butch and Suni on Starliner and gain valuable insight into system upgrades we will want to make for post-certification missions.”
Already four years behind schedule, Starliner launched June 5, a month later than planned because of minor problems with its Atlas 5 rocket, issues with a countdown computer and an initial helium leak in the system used to pressurize the capsule's thrusters.
NASA and Boeing officials decided the leak was too small to pose a safety threat and cleared the craft for launch. But once in orbit and en route to the space station, four more helium leaks occurred and Starliner’s flight computer shut down seven maneuvering jets when telemetry did not match prelaunch expectations.
One booster was deemed unusable in the future, but the others were successfully tested last Saturday. That “hot fire” test gave engineers confidence that the aircraft needed for post-undocking maneuvers and the critical deorbit “burn” will function as needed to remove the craft from orbit for reentry.
Likewise, officials said they were confident that the helium leaks could be controlled even if one or more worsen after undocking. Only seven hours of helium are needed for the return to Earth, and the Starliner has more than 10 times that amount left on board.
