With no agreement on the safety of the Starliner spacecraft, NASA officials said Wednesday they need another week or two to decide whether to return the two astronauts to Earth aboard the Boeing spacecraft or extend their stay at the International Space Station until next year.
Boeing’s Starliner spacecraft is taking up valuable space on the space station due to a thruster malfunction and a suspected helium leak, and it will need to leave the orbital laboratory before SpaceX’s next Dragon spacecraft launches to the space station on Sept. 24, with or without its two-person crew.
“If we need an extension, we can juggle things to make it work, but it’s getting more and more difficult,” said Ken Bowersox, NASA’s associate administrator for spaceflight operations. “Given the consumables that we’re using, the need to use ports for cargo missions, things like that, we’re getting to the point where we should make a decision as early as the last week of August, possibly sooner.”
NASA officials said last week they expected to make a decision in mid-August, possibly as soon as this week, but Bowersox said Wednesday that NASA probably won’t make a final decision on what to do with the Starliner spacecraft until the end of next week or early in the week of Aug. 26.
“We still have some time before we can bring Starliner home, and we want to make the most of it,” Bowersox said.
NASA astronauts Butch Wilmore and Suni Williams launched on June 5 aboard Boeing’s Starliner spacecraft. Their mission is the first crew test flight of Boeing’s capsule before NASA approves Starliner for regular crew rotation flights to the space station. But software glitches, parachute concerns and past problems with the propulsion system have kept Boeing’s Starliner program more than four years behind SpaceX’s Dragon crew spacecraft, which first carried astronauts to the space station in 2020.
And now there’s a good chance the Starliner crew won’t make it back on the spacecraft once it’s launched. Former astronaut Bowersox said NASA has brought in propulsion experts from other programs to take a fresh look at the thruster problems.
Engineers are still investigating why five of Starliner’s 28 reaction control system thrusters, supplied by Aerojet Rocketdyne, failed on approach to the space station the day after launch. The thrusters overheated as they were pulsed repeatedly to fine-tune the spacecraft’s rendezvous with the station. Tests of similar control jets on the ground found that Teflon seals on internal valves could expand at high temperatures, restricting the flow of propellant to the thrusters.
Four of the five thrusters that failed before Starliner docked with the station recovered during a test burn last month, producing near-normal thrust levels. But many NASA engineers are unsure whether the thrusters will function properly on Starliner’s journey from the space station back to Earth. These control jets are needed to keep the spacecraft pointed in the right direction as it fires its four large rocket engines for the deorbit burn that will put the capsule on a trajectory back into the atmosphere for landing.
The rapid pulse of thrusters and the extended firing of the four large engines could raise temperatures in the four doghouse-shaped propulsion pods around Starliner’s service module. Once the deorbit burn is complete, Starliner will detach the service module and let it burn up in the atmosphere while the crew module uses another set of thrusters to guide re-entry. It will then deploy a parachute to slow it down for landing, likely at White Sands, New Mexico.
Increased risk
Bowersox said outside engineers brought in from other NASA centers have so far largely agreed with the assessment of the team working full-time on Starliner.
“There are a lot of people out there who are working with similar thrusters and have had similar issues,” he said. “We’re getting feedback about what we’re seeing, and a lot of it confirms what we thought was causing the symptoms we were seeing in orbit. It’s really hard when you don’t have the hardware to actually see when you’re in space.”
