WASHINGTON – NASA and Boeing plan to keep the CST-100 Starliner spacecraft aboard the International Space Station well into July to conduct additional tests, stressing that the two-person crew is not “stranded” in space.
At a June 28 briefing on the Crew Flight Test (CFT) mission, the first in 10 days, agency and company officials said they would not set a date for Starliner’s return, which will include NASA astronauts Butch Wilmore and Suni Williams would return until additional tests were conducted to better understand thruster failures and helium leaks the spacecraft had experienced.
“Butch and Suni are not stranded in space,” said Steve Stich, NASA’s commercial crew program manager. “Our plan is to send them back on Starliner and bring them home at the right time. We still have a little more work to do to get there for the final return.”
That additional work now includes thrust tests that NASA plans to conduct at its White Sands Test Facility. Stich said NASA will take a reaction control system thrust like the one on Starliner and run it through the same profile of burns as the one on Starliner during the approach to the ISS. The goal is to see if they can reproduce the problems that caused the spacecraft to “deselect” those thrusts and perform inspections of them that are not possible in Earth orbit.
Those tests are scheduled to begin no earlier than July 2 and will last a couple of weeks, he said. “This will be the real opportunity to examine the thruster, just like we had in space on the ground, with detailed inspections.”
Only after these tests were completed and their results reviewed would NASA set a landing date for Starliner, which would be pushed back no earlier than the second half of July. That process also includes an agency-level assessment of the spacecraft to confirm that they have all the data they need to understand the cause of the problems and that the spacecraft can return home safely.
Although original plans called for Starliner to remain on the ISS for just eight days, officials said there was no rush to return home while they could still collect data, particularly from the service module section that will be jettisoned at the end of the mission and is not found. “We have the luxury of time,” said Ken Bowersox, NASA associate administrator for space operations.
“We understand these issues for a safe return,” said Mark Nappi, Boeing vice president and commercial crew program manager, about the thruster and helium leak issues. “But we don’t yet understand these problems enough to solve them permanently.”
He said the results of the ground thrust tests could lead controllers to conduct additional tests of Starliner’s thrust while the spacecraft is docked with the space station. That’s why the ground tests are being conducted before Starliner returns, not after.
NASA originally placed a 45-day limit on the length of the CFT mission based on the batteries in the crew module. However, Stich said this could be extended due to the batteries’ performance so far in the mission, without changing the risk to the mission.
The longer mission duration, coupled with problems with the thrusters and helium leaks, will pose challenges in certifying the vehicle for crew rotation missions. NASA had hoped to have Starliner certified in November, in time for a February crew rotation mission called Starliner-1.
“We understand it’s going to take a little bit longer,” Stich said of the certification. He said NASA is preparing for both Starliner-1 and Crew-10, a Crew Dragon mission scheduled for launch in late summer of next year, in parallel, meaning NASA may delay a decision on whether to advance Crew-10 until February.
“We can take our time to get the Crew Flight Test done and get the vehicle brought back with Butch and Suni, and then we can make decisions after that,” he said. “We still have time.”
During the briefing, Nappi expressed frustration over what he perceived as negative media coverage of the CFT mission. “As a representative of Boeing and the Starliner program, it is quite painful to read what is coming out,” he said. “We’ve had a really good test flight conducted so far and it’s being viewed quite negatively.”
However, many reporters on the call complained about a lack of updates on the mission and details about why the timeline for Starliner’s return kept being pushed back. “I think we probably need to communicate with the media a little more often to keep you informed,” Stich acknowledged.
Spacewalk updates
NASA also used the briefing, which lasted just over an hour, to discuss the canceled spacewalk on the space station on June 24, as well as the agency’s June 26 award of a contract to SpaceX for the U.S. Deorbit Vehicle (USDV).
The June 24 spacewalk was postponed when water leaked into the airlock after astronaut Tracy Dyson disconnected an umbilical cord from a suit just as the spacewalk began. Astronauts were unable to repair the leak, said Bill Spetch, operations integration manager for the ISS program at NASA, and the cause remains under investigation.
Emily Nelson, chief flight director, said leaks from fluid connectors are not uncommon, but they had not seen this particular leak before. “We just need to understand this specific problem in more detail before we can get the crew in line to try again.”
NASA had planned a spacewalk for July 2, but that has been postponed until the end of July, Spetch said. That spacewalk will have a different set of tasks than the June 24 spacewalk, combining tasks for what was projected as a series of three spacewalks. That work includes relocating an antenna, preparatory work for future repairs to the Alpha Magnetic Spectrometer, replacing a rate gyro assembly and swabbing parts of the station’s exterior to study any microorganisms that might live there .
When NASA announced that SpaceX had been selected as the developer of the USDV, neither the company nor the agency released details about the spacecraft’s design. This craft will be used to perform the final maneuvers to deorbit the space station at the end of its lifespan.
“That’s based on a Dragon heritage design,” Spetch said, with modifications to the trunk area. He didn’t go into details about the design and declined to discuss what differentiates it from other proposals, noting that NASA had not yet issued a source selection statement for the procurement.