Boeing Is Closer to Understanding Thruster Failures on Its First Astronaut Flight With Latest Test

The Starliner spacecraft docked to the Harmony module of the International Space Station, orbiting 262 miles above Egypt's Mediterranean coast, on June 13, 2024. NASA via AP

CAPE CANAVERAL, Fla.—Boeing is closer to understanding what went wrong with its astronaut capsule in orbit, now that testing is complete on a spare thruster here on Earth.

The Starliner capsule has been docked at the International Space Station since June 6. It should have returned with its NASA test pilots by mid-June, but thruster failures and helium leaks prompted NASA and Boeing to extend its stay.