The Boeing CST-100 Starliner crew has received encouraging news regarding its return to Earth. Recent ground testing of the spacecraft’s thrusters, which have left it stranded in orbit since early June, has now been completed. Boeing and NASA had been awaiting these tests to begin plotting the vehicle’s homeward journey.
An update provided last week indicated, “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 focusing on data reviews.” The aim of the tests was to monitor thruster degradation, helping the teams understand the reasons behind the in-flight de-selection of some thrusters and the potential effects of returning them to service for the Crew Flight Test.
The term “de-selected” refers to some thrusters ceasing to function. Tanks containing helium, which operates the thrusters, experienced leaks prior to and during the Starliner’s launch, resulting in several delays. Despite reports last month indicating that the spacecraft has more helium on board than necessary—70 hours’ worth when only seven hours are required—officials stated they are not yet ready for its return.
Previously, NASA and Boeing mentioned that a return flight could potentially occur by the end of this month. However, the timeline has become less specific: “Boeing and NASA engineers will proceed with thruster disassembly and inspections and will continue to finalize flight rationale to support readiness reviews for Starliner’s nominal return to Earth with commander Butch Wilmore and pilot Suni Williams in the coming weeks.”