Starliner Reaches Orbit Despite Thruster Problems, ISS Docking Set for Friday

Atlas V lifts off from Cape Canaveral Space Force Station with Boeing’s Starliner spacecraft. (Credit: ULA)

by Douglas Messier
Managing Editor

Boeing’s CST-100 Starliner uncrewed spacecraft reached orbit after launch from Florida on Thursday on its way to dock with the International Space Station (ISS) despite problems with two of its 12 thrusters, officials said. The flight test is a crucial step to certifying Starliner to carry crew to the station.

Boeing Vice President Mark Nappi said a Starliner thruster failed after firing for one second as the spacecraft made a burn to enter orbit after separating from its Atlas V launch vehicle. The flight software switched to a second thruster, which fired for 25 seconds before shutting down prematurely. A third thruster took over and completed the firing, Nappi said.

Despite the thruster failures, Nappi and NASA officials said the anomalies should not affect the plan to dock Starliner with the ISS on Friday at 7:10 p.m. EDT.

Steve Sich, manager of NASA’s Commercial Crew Program, said engineers are working to determine why the thrusters failed and whether they can be restored to function. Sich added that a sublimator that releases water vapor to cool the spacecraft performed sluggishly during ascent but worked as designed once the spacecraft reached orbit.

Problems with the thrusters, which are manufactured by Aerojet Rocketdyne, forced the postponement of an August launch attempt after 13 valves used in Starliner’s propulsion system failed to open on the launch pad. It’s not clear whether stuck valves were the cause of the thruster failures during Thursday’s flight.

The flight marks the second attempt by Starliner to dock with the space station. The first flight in December 2019 entered orbit, but it was unable to reach ISS due to software and communications problems. It flew an abbreviated two-day flight before landing at the White Sands Missile Range in New Mexico.

If this mission is successful, NASA astronauts will conduct a flight test of Starliner to the space station.