Boeing Starliner Launch Delayed to Address Helium Leak in Propulsion System

The United Launch Alliance Atlas 5 rocket's launch of Boeing's Starliner capsule has been postponed for an additional four days to address a small helium leak in the crew ship's propulsion system. The liftoff from pad 41 at the Cape Canaveral Space Force Station is rescheduled for 4:43 p.m. EDT on May 21 with a docking at the International Space Station expected the following afternoon. The return to White Sands, New Mexico, is anticipated around May 30.

Troubles with the Starliner's Maiden Flight

Mission commander Barry "Butch" Wilmore and co-pilot Sunita Williams were previously prepared for the Starliner's first piloted flight last Monday. However, the countdown was halted due to an issue with an oxygen pressure relief valve in the rocket's upper stage. Following this, the Atlas 5 was relocated for the replacement of the valve, while tests confirmed the rocket's readiness for another launch attempt.

Identifying the Helium Leak

During the previous countdown, an unrelated helium leak in the Starliner's propellant pressurization system was detected. The leak was located in the distribution manifold inside one of the service module's four "doghouse" assemblies. After addressing the oxygen valve issue, a closer inspection of the helium leak was conducted, and the system was deemed flight-ready following the retorquing of bolts.

Boeing will conduct further testing by pressurizing the helium lines throughout the spacecraft to ensure they are leak-free or within acceptable limits. Both Wilmore and Williams, experienced Navy test pilots and astronauts, will return to Florida for additional simulator training in preparation for the rescheduled launch.

Background on Starliner and SpaceX

Boeing's Starliner is one of two commercially built crew ferry ships commissioned by NASA to support transportation to and from the International Space Station. SpaceX was also awarded a contract, with the goal of developing independent, commercially-operated spacecraft for crew transportation.

SpaceX has made significant progress in crewed missions, having launched multiple NASA-sponsored flights and a privately-funded trip to low-Earth orbit, with a total of 50 individuals flown to space aboard Crew Dragons. Meanwhile, the Starliner faced technical challenges, including major software issues during its initial unpiloted test flight and propulsion system valve problems, delaying its second uncrewed test mission to May 2022.