Crew Boeing’s Starliner spacecraft They said Wednesday that despite a helium leak in the ship’s propulsion system and problems with its maneuvering thrusters, they were confident the capsule would carry them safely back to Earth at the end of their long stay at the International Space Station.
Launched on June 5th Commander Barry “Butch” Wilmore and co-pilot Sunita Williams Initially expected to spend eight days in space, the craft will test Starliner on its first piloted test flight.
But helium leaks and thruster problems have prompted NASA to extend the space station’s stay indefinitely (they celebrated their 35th day in orbit on Wednesday), and engineers are conducting tests and analysis to better understand what caused the problems and to make sure the spacecraft will arrive home safely to Wilmore and Williams.
Meanwhile, NASA insists crew is not ‘stranded’ in space. and Wilmore and Williams, speaking to reporters for the first time since the launch, appear to agree with that assessment.
“I’m confident that given where we are right now, what we know right now and how the spacecraft flies to dock, if there’s a problem at the International Space Station, we can get in our spacecraft, undock, talk to our crew and figure out the best way to get home,” Williams said.
“I have a really good feeling in my heart that this spacecraft will bring us home without any problems,” he added. “We’re just learning to optimize our particular situation and make sure we know everything about it.”
Asked about his belief in Starliner, Wilmore said, “We’re absolutely confident.”
“We’re actually doing thruster testing right now in White Sands, New Mexico, trying to replicate the (issues) we saw when we met,” he said. “And we’ll learn from that. And we’ll incorporate new processes, new procedures that we’ll use if necessary.”
But to be on the safe side, Steve Stich, NASA Commercial Crew Program manager, said the team had “dusted off” the initial plans when a coolant leak occurred on the Russian Soyuz spacecraft carrying NASA astronaut Frank Rubio to the station.
In that case, preliminary plans were made to land Rubio in a SpaceX Crew Dragon capsule if worse came to worst. Eventually, the Russians launched a backup Soyuz, making those plans unnecessary.
“In this case, we decided to use Dragon as an emergency return option for Frank… to use it as a lifeboat,” Stich said. “Dragon had a configuration of Frank on the mid-deck. So, we definitely dusted off a few of those to look at against Starliner, just to be prepared.
“But again, our primary option is to return Butch to Suni on Starliner. … We’re a long way from where we were with Soyuz. We want to understand the thrusters a little bit more before we make a final decision on separation and return.”
After multiple delays, we’re ‘having a great time’ in orbit
In the meantime, Williams said he and Wilmore are enjoying the extra time spent in space.
“We’re having a great time on the ISS,” he said. “Butch and I have been here before, and it feels like… coming home. It feels good to be floating around. It feels good to be in space and working with the International Space Station crew here.
“So, yeah, it’s great to be here,” he said. “I mean, I’m not complaining, Butch isn’t complaining about us being here for a few more weeks.”
Four years behind schedule, Starliner launched on June 5, a month later than planned, due to minor issues with the crew’s Atlas 5 booster, a problem with the countdown computer and a small helium leak in the capsule’s rear service module. Helium is used to pressurize the Starliner’s propulsion system so the jets can fire as needed.
After extensive analysis, NASA and Boeing executives determined that the leak was not a security threat and the Starliner was allowed to launch as is.
But after entering orbit and en route to the space station, four more helium leaks occurred. Additionally, Starliner’s flight computer disabled several rear-facing maneuvering jets when telemetry did not match preset operating parameters.
One booster was deemed unusable in the future, but others were later tested successfully. This “hot fire” test gave engineers confidence that the jets needed for post-separation maneuvers and to keep the Starliner steady during the critical deorbit rocket firing would function as they should to prepare the ship for reentry.
Those thrusters were facing the sun during Starliner’s long approach to the station, and engineers suspect that previous problems were related to the high temperatures and speed of the firings during final approach. They are trying to replicate those conditions in ground tests.
As for helium leaks, the propulsion system is not used while docked to the space station. The system was pressurized for the hot fire test, but otherwise the valves were closed to isolate the helium tanks as always planned, eliminating any additional leaks.
The system will be re-pressurized during departure to allow for the maneuvers needed to return home. But engineers said there was 10 times more helium in the tanks than needed for the return trip, providing a comfortable margin even if any of the known leaks worsened.
“I anticipate that we will do tests before we leave the ground, actually opening the helium valves first and then after we leave the ground to make sure everything is working correctly, as planned, as they found in the thruster test,” Williams said. “So I have confidence, Butch has confidence.”
All of that hardware is housed in Starliner’s service module, which is jettisoned just before re-entry, so engineers will never be able to inspect the equipment firsthand. Williams said it made sense to extend the mission to get as much testing done as possible before returning home.
“If we had just returned home, we would have lost the SM (service module) and then we wouldn’t have been able to do all these tests and learn about our spacecraft,” he said.
Stich did not say when the crew might get permission to leave. The next Crew Dragon crew rotation flight is scheduled to launch in mid-August, and “a few days before that launch opportunity, we’ll need to get Butch and Suni home on the Starliner.”
“This is kind of the back end,” he said. “We’re really working on tracking the data and trying to see when the earliest we can target for separation and landing. I think some of the data is, maybe optimistically, indicating late July. But we’ll just track the data (and) figure out when the right separation opportunity is.”
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