The crew of the Boeing CST-100 Starliner received some positive news regarding their return to Earth. Recently, ground testing for the spacecraft’s thrusters was completed, which had been the cause of the vessel remaining in space since early June. Boeing and NASA were awaiting the conclusion of these tests before planning for the spacecraft’s journey home.
An update shared late last week noted, “Ground testing of a Starliner Reaction Control System (RCS) thruster at White Sands Test Facility in New Mexico is complete, and teams are now turning their attention to data reviews.” The purpose of the tests was to investigate thruster degradation, helping teams understand the issues that led to some thrusters being deselected during flight and assess the potential implications of reactivating those thrusters.
The term “de-selected” refers to thrusters that ceased functioning. Before and during the Starliner launch, leaks were detected in the helium tanks responsible for controlling the thrusters, contributing to numerous delays. At a press conference last month, officials revealed that the spacecraft holds 70 hours’ worth of helium, despite only needing seven. While they stated that the spacecraft could return immediately if necessary, they also acknowledged that preparations were not quite finished.
Previously, NASA and Boeing indicated that a return flight could occur at the end of this month. However, the timeline is now 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.”