NASA leaders, including agency head Bill Nelson, are meeting in Houston on Saturday to decide whether Boeing's Starliner spacecraft is safe enough to transport astronauts Butch Wilmore and Suni Williams back to Earth from the International Space Station.
The Flight Readiness Review (FRR) is expected to result in NASA's most consequential safety decision in nearly a generation. One option is to allow the Starliner space capsule to undock from the space station in early September with Wilmore and Williams on board, as its original flight plan called for, or to bring the capsule home without a crew.
As of Thursday, the two experienced astronauts have now been on the space station for 77 days, almost ten times longer than their planned eight-day stay. Wilmore and Williams were the first humans to launch and dock with the space station aboard a Starliner spacecraft, but several engines failed and the capsule lost helium from its propulsion system as it approached the orbital complex on June 6.
That led to months of testing – in space and on the ground – data reviews and modeling to help engineers understand the root cause of the engine problems. Engineers believe the engines overheated, causing Teflon seals to bulge and block the flow of fuel to the small control nozzles, resulting in a loss of thrust. The condition of the engines improved after Starliner docked with the station and they no longer fired as often as a spacecraft flying alone must.
However, engineers and managers are not yet sure whether the same problem could reoccur or even worsen during the capsule's return trip to Earth. In the worst case scenario, if too many engines fail, the spacecraft might not point in the right direction to guide the capsule back into the atmosphere for landing with a critical braking shock.
The suspect thrusters are located on the Starliner's service module, which performs the deorbit burn and then separates from the astronaut crew module before reentry. A separate set of small thrusters will fine-tune the Starliner's trajectory during descent.
If NASA managers decide it's not worth the risk, Wilmore and Williams could extend their stay on the space station until at least February of next year and then return to Earth in a Dragon spacecraft from SpaceX, Boeing's rival in NASA's commercial crew program. This would eliminate the threat that engine problems on the Starliner spacecraft could pose to the crew's safety during the trip to Earth, but brings with it myriad side effects.
These impacts include the disruption of crew activities on the space station due to the denial of two astronauts on the next SpaceX flight, the additional radiation exposure of Wilmore and Williams during their stay in space, and a major blow to Boeing's Starliner program.
If Boeing's capsule with its two astronauts cannot return to Earth, NASA may not approve Starliner for operational crew missions without an additional test flight. In that case, Boeing would likely be unable to complete all six planned operational crew missions under a $4.2 billion NASA contract before the International Space Station is decommissioned in 2030.
FRR-Freedom to speak
The Flight Readiness Review at NASA's Johnson Space Center in Houston begins Saturday morning. Ken Bowersox, former astronaut and head of NASA's Space Operations Mission Directorate, will lead the session. NASA Administrator Bill Nelson will also attend. If there is no unanimous agreement at the FRR table, the final decision on how to proceed could go beyond Bowersox to NASA Deputy Administrator Jim Free or to Nelson.
“During the agency's flight readiness review, any formal disagreements are brought forward and resolved,” NASA said in a statement Thursday. “Other agency leaders who regularly participate in launch and return readiness reviews for human missions include the administrator, deputy administrator, associate administrator, various agency center heads, the Flight Operations Directorate, and agency technical authorities.”
NASA has scheduled a press conference for no earlier than 1 p.m. ET (5 p.m. UTC) on Saturday to announce the decision and the agency's next steps, the agency said.
Lower-level executives will meet Friday in what is known as a Program Control Board to discuss their findings and views ahead of the FRR. At an earlier Program Control Board meeting, managers disagreed on whether the agency was ready to certify that the Starliner spacecraft was safe enough to return its astronauts to Earth.
There is new information that the engineers will present to the Program Control Board on Friday:
“Engineering teams are working to evaluate a new model representing the engine mechanics that is designed to more accurately predict performance during the return phase of flight,” NASA said. “This data could 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 feed into the agency-level review.”