Amid a lack of consensus on the safety of the Starliner crew capsule, NASA officials said Wednesday they need another week or two before deciding whether to take the two astronauts back to Earth on a Boeing spacecraft or extend their stay on the International Space Station into next year.
Boeing’s Starliner spacecraft, crippled by questionable engines and helium leaks, is taking up valuable parking space on the space station. It must leave the orbiting research elaborate, with or without a two-person crew, ahead of the launch of SpaceX’s next crewed Dragon mission to the station, scheduled for September 24.
“We can juggle things and make it work if we need to expand, but it’s getting harder and harder,” said Ken Bowersox, associate administrator for NASA’s spaceflight operations directorate. “Because of the consumables we’re using, because of the need to use ports for cargo missions, things like that, we’re getting to the point where we really should have made a decision by the last week of August, if not sooner.”
NASA officials said last week they expected to make a decision in mid-August — possibly this week — but Bowersox said Wednesday that NASA likely won’t make a final decision on what to do with the Starliner spacecraft until the end of next week or the beginning of the week of Aug. 26.
“We have time before we bring Starliner home, and we want to use it wisely,” Bowersox said.
NASA astronauts Butch Wilmore and Suni Williams blasted off June 5 inside Boeing’s Starliner spacecraft. Their mission is the first crewed test flight of a Boeing capsule before NASA allows Starliner to make regular rotational crew flights to the space station. But after software setbacks, parachute concerns and earlier propulsion system issues, Boeing’s Starliner program is running more than four years behind SpaceX’s crewed Dragon spacecraft, which first carried astronauts to the station in 2020.
And now there’s a good chance the Starliner crew won’t be returning home on the spacecraft they took off in. Bowersox, a former astronaut, said NASA has brought in propulsion experts from other programs to take a fresh look at the engine problem.
Engineers are still investigating why five of Starliner’s 28 reaction system thrusters, supplied by Aerojet Rocketdyne, failed during approach to the space station the day after launch. The thrusters overheated as they pulsed repeatedly to fine-tune the spacecraft’s rendezvous with the station. Tests of a similar thruster on the ground suggested that a Teflon seal in an internal valve could swell at higher temperatures, restricting fuel flow to the thruster.
Four of the five engines that failed before Starliner docked with the station recovered and produced near-normal thrust levels during test firings last month. But many NASA engineers are not convinced the engines will function normally during Starliner’s journey from the space station back to Earth. These thrusters are needed to keep the spacecraft pointed in the right direction when the four larger rocket engines are fired to deorbit the capsule and put it on a trajectory back into the atmosphere for landing.
Rapid thruster pulsations, combined with long firings of four larger engines, could raise temperatures inside the four budo-buds around the perimeter of the Starliner service module. Once the deorbit burn is complete, Starliner will eject the service module to burn up in the atmosphere, and its crew module will utilize another set of thrusters to guide its return. It will then deploy parachutes to sluggish for a landing, probably at White Sands, Recent Mexico.
Increased risk
Bowersox said outside engineers brought in from other NASA facilities have so far largely agreed with the assessments made by the full-time Starliner team.
“There are a lot of people who have worked with similar engines and seen similar problems,” he said. “So we got feedback on what we were seeing, and a lot of it confirmed what we thought was causing the signatures we were seeing in orbit. It’s really hard when you don’t have the actual equipment to look at when you’re in space.”