The return of Boeing’s Starliner capsule to Earth is suspended indefinitely The results of new engine tests and ongoing analysis of helium leaks that occurred during the ship’s rendezvous with the International Space Station are still pending, NASA said Friday.
Agency officials stressed, however, that Starliner commander Barry “Butch” Wilmore and co-pilot Sunita Williams were not “stranded” in space.
NASA
“We don’t have a target date for landing today,” Steve Stich, NASA’s commercial crew program manager, told reporters during a conference call. “We won’t target a specific date until we’ve completed testing.”
“So essentially it’s about completing the testing, completing the fault tree, presenting that analysis to the mission management team and then doing an agency-level review. And then we’ll lay out the rest of the plan, from undocking to landing. I think we’re well on our way.”
The Problem for NASA and Boeing is that the Starliner’s service module, which houses the helium lines, engines and other critical systems, is jettisoned before re-entry and burns up in the atmosphere.
Since the engineers cannot examine the hardware afterwards, they want to collect as much data as possible before Wilmore and Williams return home.
But the crew’s repeated extensions of their stay on the space station during this analysis led some observers to believe that Wilmore and Williams were stranded in orbit. This impression seems to have been reinforced by the lack of updates from NASA, as the planned landing date was repeatedly pushed back.
Stich and Mark Nappi, Boeing’s Starliner program manager, said that description was a misrepresentation.
“It’s pretty painful to read the things that are out there,” Nappi said. “We had a really good test flight … and it’s being reviewed rather negatively. We’re not stuck on the ISS. The crew is not in danger and there’s no increased risk if we decide to bring Suni and Butch back to Earth.”
Stich added that he wanted to “make it very clear that Butch and Suni are not stranded in space. Our plan is to continue to bring them back on the Starliner and bring them home at the right time. We’ll have a bit of work to do to get to where they can finally return, but they are safe on the space station. Their spacecraft is working well and they are enjoying their time on the space station.”
The Starliner launched on the program’s first crewed test flight on June 5 with one previously known helium leak. The other four occurred during the ship’s rendezvous with the space station, when the thrusters were rapidly pulsed to optimize the Starliner’s approach.
United Starting Alliance
While docked at the station, the valves are closed to isolate the helium system and prevent further leaks. However, once Wilmore and Williams depart and head home, the valves will be reopened to repressurize the lines or manifolds.
Stich said that even with the known leaks, the spacecraft would have 10 times the amount of helium it needed for the trip home, but engineers wanted to make sure the leaks wouldn’t get worse when the system was repressurized.
The five rear-facing engines in the Starliner’s service module also did not function as expected during the approach to the space station on June 6.
After docking, four of the five engines were successfully tested and although their performance was slightly lower than expected, they are considered ready for undocking and reentry. The fifth engine was not “hot fired” because its previous performance suggested that it had actually failed.
But managers want to find out what caused the other four to behave unexpectedly. Starting next week, a new engine identical to the one on board the Starliner will be tested at a government facility in White Sands, New Mexico, in the same way the engines were fired in orbit during the Starliner’s rendezvous and docking.
“We’re going to replicate that profile,” Stich said. “Then we’re going to build a pretty aggressive profile into the engine for the phase from undocking to re-entry.”
NASA
It is possible that the rear-facing engine malfunctions were caused by higher than normal temperatures due to the Starliner’s orientation toward the sun, or by the sequence of rapid, repeated firings controlled by the flight software. Or both.
The soil tests, which are expected to take “a few weeks,” could provide evidence one way or the other.
“This is a real opportunity to examine an engine in the same way we did in space on Earth, a detailed inspection,” Stich said. “Once those tests are complete, we’ll look at the plan for landing.”
As for the impression that the crew was stranded in space, Stich and Nappi both pointed out that a catastrophic “event” occurred on Wednesday involving a defunct Russian satellite in a slightly lower and more inclined orbit than that of the space station, sending more than 100 trackable pieces of debris flying.
While flight controllers assessed the trajectory of the debris, the space station’s nine-member crew was ordered to seek shelter in their respective spacecraft and be ready to immediately take off and return to Earth in the event of a destructive impact.
Two Russian cosmonauts and NASA’s Tracy Dyson boarded their Soyuz cargo craft, while three NASA astronauts and another cosmonaut floated into their SpaceX Crew Dragon. Wilmore and Williams left the safety of the Starliner and were cleared to fly home if needed.
After about an hour, the crew was given the green light to return to normal operations. Had the Starliner been deemed unsafe, Wilmore and Williams would likely have been ordered to seek refuge in the Crew Dragon. But that was not the case.
“We are approved to act as a lifeboat on the ISS in the event of an emergency,” Nappi said. “That means we can return with the Starliner at any time, and that was proven this week.”