It wasn’t perfect, but the propulsion system that NASA worried about did its job today as Boeing’s Starliner space capsule made an uncrewed descent from the International Space Station back down to Earth.
The gumdrop-shaped spacecraft, christened Calypso, floated down to a parachute-assisted, airbag-cushioned touchdown at White Sands Space Harbor in New Mexico. “Starliner is back on Earth,” Boeing commentator Lauren Brennecke said.
Starliner’s first crewed trip to the space station was supposed to last only about a week, but when the capsule made its approach for docking on June 6, five thrusters out of a set of 28 malfunctioned. Four of the thrusters were reactivated, and NASA astronauts Butch Wilmore and Sunita Williams executed a successful docking. But concerns about the thrusters — and about a string of helium leaks in the propulsion pressurization system — sparked weeks of troubleshooting by NASA and Boeing.
Engineers decided that they could cope with the helium leaks, but the thruster problem was a bigger concern. Tests determined that the propulsion system’s performance was degraded by overheating that exceeded design specifications.
Two weeks ago, NASA said the uncertainties surrounding the system’s performance were too great to risk having Williams and Wilmore ride back to Earth on Starliner. Instead, the astronauts were told to remain on the station for months longer than originally planned.
To accommodate the personnel shift, NASA reduced the size of the next scheduled crew, known as Crew-9, from four to two spacefliers. That crew is due to go into orbit in a SpaceX Crew Dragon capsule on Sept. 24. Williams and Wilmore will join Crew-9 and return to Earth in the SpaceX capsule next February.
