"We’ll continue to work through certification toward the end of this year."
Boeing's Starliner spacecraft undocks from the International Space Station at the conclusion of an unpiloted test flight in May 2022. Credit: NASA
More than half a year after an empty Starliner spacecraft safely landed in a New Mexico desert, NASA and Boeing still have not decided whether the vehicle's next flight will carry any astronauts.
In an update this week, the US space agency said it is still working through the process to certify Starliner for human missions. Whether it carries cargo or humans, Starliner's next flight will not occur until late this year or, more likely, sometime in 2026.
Two things stand out in the new information provided by NASA. First, there remains a lot of work left to do this year before Starliner will fly again, including extensive testing of the vehicle's propulsion system. And secondly, it is becoming clear that Starliner will only ever fly a handful of missions to the space station, if that, before the orbiting laboratory is retired.
Long line of tests
Several issues marred Starliner's first crew flight to the space station last June, but the most serious of these was the failure of multiple maneuvering thrusters. Concerns about these thrusters prompted NASA to fly Starliner's crew, Butch Wilmore and Suni Williams, home on a Crew Dragon vehicle instead. They safely landed earlier this month.
Starliner returned autonomously in early September. Since then, NASA and Boeing have been reviewing data from the test flight. (Unfortunately, the errant thrusters were located on the service module of the spacecraft, which is jettisoned before reentry and was not recovered.)
Although engineers from NASA and Boeing have worked through more than 70 percent of the observations and anomalies that occurred during Starliner's flight, the propulsion system issues remain unresolved.
To address these issues, NASA said it is finalizing a test campaign that will take place this spring and summer. "Testing at White Sands Test Facility in New Mexico will include integrated firing of key Starliner thrusters within a single service module doghouse to validate detailed thermal models and inform potential propulsion and spacecraft thermal protection system upgrades, as well as operational solutions for future flights," the agency said in its update this week.
As far as those potential solutions go, one option is the installation of thermal barriers to better control temperatures and prevent overheating observed during Starliner's last two spaceflights. Steve Stich, manager of NASA’s Commercial Crew Program, said the agency will have a better idea of when Starliner will fly again after these tests and analyses are complete.
"We’ll continue to work through certification toward the end of this year and then go figure out where Starliner fits best in the schedule for the International Space Station and its crew and cargo missions," Stich said. "It is likely to be in the timeframe of late this calendar year or early next year for the next Starliner flight."
Cargo or crew?
NASA has not determined whether such a mission will carry cargo or crew. The agency's update said that it will depend on the operational needs of the station. However, it seems clear that if there are still some unresolved questions about the propulsion system issues, NASA may opt for what would essentially be another test flight of Starliner that also brings cargo to the space station.
A cargo flight would, effectively, be the fourth test flight of Starliner, dating back to its first mission in December 2019.
NASA's update this week did answer one question that had been hanging over the Starliner program. Although Boeing has taken losses in excess of $2 billion on its fixed-price contract with NASA, the company now appears committed to seeing the certification process through. NASA likely has applied pressure for Boeing's ongoing participation as the space agency desires to have two crew transportation providers to the space station.
Yet time is running out for Boeing to make a considerable impact on crew flights to the International Space Station, which is due to be retired in 2030. Assuming an operational crew flight in 2026—which seems far from a certainty—Starliner would likely fly four, or at the very most five, crewed missions to the space station. The initial contracts that NASA signed with SpaceX and Boeing for crew transportation services more than a decade ago had options for as many as six crew rotation flights to the station after certification.
To date, NASA has only given Boeing "Authority To Proceed" for three of its six potential operational Starliner missions. This milestone is a decision point in contracting lingo where the customer—in this case, NASA—places a firm order for a deliverable. NASA has extended SpaceX's commercial crew contract to cover as many as 14 Dragon missions with astronauts.
SpaceX, in fact, has now launched 10 operational crew missions to the station. On Thursday, NASA announced the crew for SpaceX's 11th mission, Crew-11, which will launch no earlier than July. Among the astronauts were two people previously assigned to Starliner's first operational mission, NASA's Mike Fincke and Japanese Mission Specialist Kimiya Yui.