The crew of the Boeing CST-100 Starliner has recently received positive news regarding their anticipated return to Earth. Earth-based testing of the spacecraft’s thrusters, which have left it in orbit since early June, has been completed. Boeing and NASA had been waiting for these tests to conclude before planning the spacecraft’s homeward journey.
“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 focused on reviewing the data,” an update released last week stated. The objective of the tests was to examine the degradation of the thrusters to better understand why some were inactive during flight and consider the possible implications of returning those thrusters to service for the remainder of the Crew Flight Test.
The term “de-selected” refers to the thrusters that ceased functioning. Prior to and during the Starliner’s launch, there were leaks in the helium tanks that control the thrusters, resulting in multiple delays. During a press conference last month, officials noted that the spacecraft has 70 hours’ worth of helium on board, despite only requiring seven hours’ worth. Although they mentioned earlier this month that the craft could return immediately if necessary, they also indicated that they are not fully prepared for that eventuality.
In their latest update, NASA and Boeing indicated that a return flight might occur at the end of this month, but this timeline has now become less specific: “Boeing and NASA engineers will proceed with thruster disassembly and inspections, and will also finalize flight rationale in support of readiness reviews for Starliner’s planned return to Earth with commander Butch Wilmore and pilot Suni Williams in the upcoming weeks.”