The crew of the Boeing CST-100 Starliner received encouraging news regarding their return to Earth. Ground testing of the spacecraft’s thrusters, which have left it in orbit since early June, has recently concluded. Boeing and NASA were awaiting these tests to begin planning the spacecraft’s homeward journey.
An update released last week reported, “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 objective of these tests was to monitor thruster performance and degradation, which will help understand why certain thrusters were inactive during the flight and assess any implications for bringing them back into service.
Some thrusters had been “de-selected” due to malfunctions. Leaks in the helium tanks that control the thrusters were identified before and during the Starliner launch, causing multiple delays. At a press conference last month, officials highlighted that the spacecraft was equipped with 70 hours of helium, whereas only seven hours were needed for its operation. Although they indicated the craft could return immediately if necessary, they also mentioned that they were not ready for that eventuality yet.
NASA and Boeing previously suggested that a return flight could occur by the end of this month; however, the timeline has become less specific. The latest update states, “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.”