The crew of the Boeing CST-100 Starliner is receiving encouraging news regarding its return to Earth. Recent ground tests on the spacecraft’s thrusters, which have left it grounded in space since early June, have now been completed. Boeing and NASA were waiting for these tests to finish before they could begin planning the vehicle’s return journey.
An update released last week confirmed that the ground testing of a Starliner Reaction Control System (RCS) thruster at the White Sands Test Facility in New Mexico has been completed, and teams are now focused on reviewing the data. The goal of the tests was to assess thruster degradation to better understand why certain thrusters were de-selected during the flight and to evaluate any potential impacts of bringing those thrusters back into service for the upcoming Crew Flight Test.
The term “de-selected” refers to thrusters that became non-functional. Prior to and during the Starliner launch, there were leaks in the helium tanks that control the thrusters, resulting in several delays. Officials indicated last month that the spacecraft has 70 hours of helium onboard, although it only requires seven. They mentioned earlier this month that the craft could return immediately if necessary, but clarified that they are not fully prepared for that return just yet.
In their latest update, NASA and Boeing suggested that a return flight might occur at the end of this month. However, the timeline has become less definitive: “Boeing and NASA engineers will proceed with thruster disassembly and inspections, and will continue 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.”