The Boeing CST-100 Starliner is showing promising signs of progress toward its return to Earth. Recent ground testing of the spacecraft’s thrusters, which have left it stranded in space since early June, has been completed. NASA and Boeing were awaiting the results of these tests to begin preparations for the vessel’s homecoming.
An update released last week confirmed the successful ground testing of a Starliner Reaction Control System (RCS) thruster at the White Sands Test Facility in New Mexico. The testing aimed to identify thruster degradation and better understand the issues that caused certain thrusters to be de-selected during flight, as well as to evaluate the potential impact of reactivating those thrusters on the upcoming Crew Flight Test.
The term “de-selected” refers to thrusters that ceased functioning. The helium tanks that control these thrusters had leaks before and during the Starliner launch, resulting in multiple delays. Despite having 70 hours of helium onboard — well beyond the required seven hours — officials indicated that while the spacecraft could return immediately if necessary, they are not yet fully prepared for that eventuality.
In the most recent update, NASA and Boeing mentioned that a return flight could be possible by the end of this month. However, the timeline now seems less definitive. Engineers at Boeing and NASA will conduct disassembly and inspection of the thrusters while continuing to finalize the flight rationale to ensure readiness for Starliner’s anticipated return to Earth, with commander Butch Wilmore and pilot Suni Williams aboard, in the coming weeks.