Enlarge / Boeing’s Starliner spacecraft on final approach to the International Space Station last month. (credit: NASA)

Before clearing Boeing’s Starliner crew capsule to depart the International Space Station and head for Earth, NASA managers want to ensure the spacecraft’s problematic control thrusters can help guide the ship’s two-person crew home.

The two astronauts who launched June 5 on the Starliner spacecraft’s first crew test flight agree, although they said Wednesday that they’re comfortable with flying the capsule back to Earth if there’s any emergency that might require evacuation of the space station.

Five of the 28 reaction control system thrusters on Starliner’s service module dropped offline as the spacecraft approached the space station last month. Starliner’s flight software disabled the five control jets when they started overheating and losing thrust. Four of the thrusters were later recovered, although some couldn’t reach their full power levels as Starliner came in for docking. In mid-June, the Starliner astronauts hot-fired the thrusters again, and their thrust levels were closer to normal.

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