The Boeing CST-100 Starliner crew has received encouraging news regarding their return to Earth. Recent ground testing of the spacecraft’s thrusters has been completed, which were responsible for keeping it in space since early June. Boeing and NASA had been awaiting the conclusion of these tests to initiate plans for the vehicle’s return journey.
The update from last week stated, “Ground testing of a Starliner Reaction Control System (RCS) thruster at the White Sands Test Facility in New Mexico is complete, and teams are now turning their attention to data reviews.” The purpose of these tests was to evaluate thruster degradation in order to understand why some thrusters were not operational during flight and assess the implications of potentially returning them to service for the Crew Flight Test.
The term “de-selected” refers to thrusters that ceased functioning. Prior to and during Starliner’s launch, the helium tanks controlling the thrusters experienced leaks, leading to several delays. At a press briefing the previous month, officials confirmed that the spacecraft carries 70 hours’ worth of helium, despite requiring only seven hours. While they previously indicated the Starliner could return immediately if necessary, they stated that preparations for its return are still ongoing.
In their latest update, NASA and Boeing suggested that a return flight could occur by the end of this month. However, the timeline has since become less specific: “Boeing and NASA engineers will proceed with thruster disassembly and inspections, and move forward with finalizing flight rationale in support of readiness reviews for Starliner’s nominal return to Earth with commander Butch Wilmore and pilot Suni Williams in the coming weeks.”