Anika Begay
In the absence of a consensus on the safety of the Starliner crew capsule, NASA officials said Wednesday they will need another week or two before deciding whether to return two astronauts to Earth aboard the Boeing spacecraft or extend their stay on the International Space Station into next year.
Boeing’s Starliner spacecraft, battered by suspicious thrusters and a helium leak, is taking up valuable parking space on the space station. It must leave the orbiting research complex, with or without its two-person crew, before SpaceX’s next crewed Dragon mission to the station launches Sept. 24.
“We can juggle things and make things work if we need to extend them, but it’s getting a lot harder,” said Ken Bowersox, associate administrator of NASA’s Space Flight Operations Directorate. “With the consumables that we’re using, with the need to use the ports for cargo missions, those types of things, we’re getting to a point where that last week of August, we really need to make a decision, if not sooner.”
NASA officials said last week that they expected to make a decision in mid-August, presumably this week, but Bowersox said Wednesday that NASA likely won’t make a final decision on what to do with the Starliner spacecraft until late next week or early 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 launched aboard Boeing’s Starliner spacecraft on June 5. Their mission is the first crew test flight in Boeing’s capsule before NASA clears Starliner for regular crew rotation flights to the space station. But after software setbacks, issues with its parachute and previous problems with its propulsion system, 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 significant chance the Starliner crew won’t return home on the spacecraft they launched on. Bowersox, a former astronaut, said NASA has brought in propulsion experts from other programs to take a fresh look at the thruster problem.
Engineers are still investigating the root cause of why five of Starliner’s 28 reaction control system thrusters, supplied by Aerojet Rocketdyne, failed during the approach to the space station the day after launch. The thrusters overheated as they pulsed repeatedly to fine-tune the ship’s rendezvous with the station. Tests of a similar control jet on the ground suggested that a Teflon gasket in an internal valve could swell at higher temperatures, restricting the flow of propellant to the thruster.
Four of the five thrusters that failed before Starliner docked with the station have recovered and generated near-normal levels of thrust during firing tests last month. But many NASA engineers aren’t convinced the thrusters will function normally during Starliner’s journey from the space station to Earth. These control jets are needed to keep the spacecraft pointed in the right direction when four larger rocket engines ignite for a deorbit burn to guide the capsule back into the atmosphere for landing.
Rapid thruster pulses, combined with a long burn of the four largest engines, could raise temperatures inside four doghouse-shaped propulsion pods around the perimeter of Starliner’s service module. Once its deorbit burn is complete, Starliner will jettison its service module to burn up in the atmosphere, and its crew module will use a different set of thrusters to drive its reentry. It will then deploy parachutes to slow its landing, likely at White Sands, New Mexico.
High risk
Bowersox said that outside engineers from other NASA centers have so far largely agreed with the assessments made by the team working full-time on Starliner.
“There are a lot of people out there who have worked with similar thrusters and seen similar problems,” he said. “So we’ve gotten feedback on what we’re seeing, and a lot of it confirms what we thought was causing the signatures we were seeing in orbit. It’s really tough when you don’t have the actual hardware to look at, when it’s in space.”
