Top NASA executives, including Bill Nelson, the agency's director, are meeting in Houston on Saturday to decide whether Boeing's Starliner spacecraft is safe enough to return astronauts Butch Wilmore and Suni Williams to Earth from the International Space Station.
The Flight Readiness Review (FRR) is expected to conclude with NASA's most consequential safety decision in nearly a generation. One option is to undock the Starliner spacecraft from the space station in early September with Wilmore and Williams aboard, as their flight plan originally called for, or to bring the capsule home without a crew.
As of Thursday, the two veteran astronauts had been on the space station for 77 days, nearly 10 times longer than their planned eight-day stay. Wilmore and Williams were the first people to launch and dock with the space station aboard a Starliner spacecraft, but multiple thrusters failed and the capsule began leaking helium from its propulsion system as it approached the orbit it completed on June 6.
That led to months of testing — in space and on the ground — data review and modeling for engineers to try to understand the root cause of the thrusters’ problems. Engineers believe the thrusters overheated, causing their Teflon seals to swell and block the flow of propellant to the small control jets, causing them to lose thrust. The condition of the thrusters improved when Starliner docked with the space station, when they weren’t firing repeatedly, as they must when the spacecraft is flying alone.
Engineers and managers, however, have not yet reached a consensus on whether the same problem could happen again or get worse during the capsule's journey back to Earth. In the worst case, if too many thrusters fail, the spacecraft would not be able to point in the right direction for a critical brake burn to guide the capsule back into the atmosphere toward landing.
The suspected thrusters are on Starliner’s service module, which will perform the deorbit burn and then separate from the astronaut-carrying crew module for reentry. A separate set of small engines will fine-tune Starliner’s trajectory during descent.
If NASA officials decide it’s not worth the risk, Wilmore and Williams would extend their stay on the space station until at least February of next year, then return to Earth aboard a Dragon spacecraft operated by SpaceX, Boeing’s rival in NASA’s commercial crew program. That would eliminate the threat that problems with the Starliner spacecraft’s thruster could pose to the crew’s safety on the journey back to Earth, but it comes with numerous side effects.
These effects include disrupting space station crew operations by pulling two astronauts from the next SpaceX flight, exposing Wilmore and Williams to additional radiation during their time in space, and dealing a devastating blow to Boeing's Starliner program.
If Boeing’s capsule can’t return to Earth with its two astronauts, NASA might not be able to certify Starliner for operational crew missions without an additional test flight. In that case, Boeing likely wouldn’t be able to complete all six planned operational crew missions under NASA’s $4.2 billion contract before the International Space Station is due to retire in 2030.
FRR Right to Speak
The Flight Readiness Review begins Saturday morning at NASA's Johnson Space Center in Houston. Ken Bowersox, a former astronaut and head of NASA's Space Operations Mission Directorate, will chair the meeting. NASA Administrator Bill Nelson will also participate. If there is not unanimous agreement around the table at the FRR, a final decision on what to do could be deferred from Bowersox to NASA's associate administrator, Jim Free, or to Nelson.
“The agency's flight readiness review is where formal disagreements are presented and reconciled,” NASA said in a statement Thursday. “Other agency leaders who routinely participate in launch and return readiness reviews for crewed missions include NASA's administrator, deputy administrator, associate administrator, various agency center directors, the Flight Operations Directorate, and the agency's technical authorities.”
NASA has scheduled a news conference no later than 1 p.m. ET (17:00 UTC) Saturday to announce the agency's decision and next steps, the agency said.
Lower-level executives are meeting Friday in a so-called Program Control Board to discuss their findings and positions for the FRR. During an earlier Program Control Board meeting, executives disagreed over whether the agency was prepared to certify that the Starliner spacecraft was safe enough to return its astronauts to Earth.
There is one new piece of information that engineers will present to the Program Control Board on Friday:
“Engineering teams have been working to evaluate a new model that represents thrust mechanics and is designed to more accurately predict performance during the reentry phase of flight,” NASA said. “These data can help teams better understand system redundancy from undocking to service module separation. Ongoing efforts to complete the new modeling, characterize spacecraft performance data, refine integrated risk assessments, and determine community recommendations will be incorporated into the agency-level review.”
