Plans to launch Boeing's often-delayed Starliner spacecraft on its first crewed test flight Saturday were suspended Tuesday night to give managers more time to evaluate a small helium leak in the ship's propulsion system. A new release target was not announced.
The Starliner crew, Commander Barry “Butch” Wilmore and co-pilot Sunita Williams, remained at the Johnson Space Center in Houston waiting to hear when to head to the Kennedy Space Center to make final preparations for the launch to the International Space Station.
United Launch Alliance
They had hoped to lift off at 3:09 p.m. EDT Saturday, assuming NASA and Boeing administrators agreed it would be safe to launch the spacecraft “as is,” with a small but persistent leak in the pressurization system. propulsion of the ship.
But multiple sources said earlier Tuesday that that option was no longer on the table, as additional meetings were planned to discuss the rationale for launching the spacecraft assuming the leak did not worsen in flight.
In a brief statement Tuesday afternoon, NASA said that “the team has been in meetings for two consecutive days, evaluating flight justification, system performance, and redundancy. There is still work ahead in these areas, and the next possible launch opportunity is still being discussed.
NASA did not announce when the analysis might be completed or when another launch attempt might be made. Short-term launch opportunities beyond Saturday and Sunday, based on the Starliner's ability to match the station's orbit, are May 28 and June 1, 2, 5 and 6.
The latest delay was a familiar setback for the Starliner, which has suffered a steady stream of frustrating complications since an initial unmanned test flight in 2019 was derailed by software problems and communications errors. A second unmanned test flight was launched and, although generally successful, more problems were discovered after its return to Earth.
The helium leak was first detected during a launch attempt on May 6. At the time, engineers concluded that the leak rate was small enough to allow launch, but the the countdown was cancelled after engineers at Atlas-builder United Launch Alliance noticed unusual behavior in an oxygen pressure relief valve on the Centaur rocket's upper stage.
Ultimately, managers decided to take the rocket back to the company's vertical integration facility to replace the valve. This work was completed without incident and the new valve was cleared for flight.
Boeing engineers used the delay to conduct a more thorough assessment of the helium leak, which was traced to a specific thruster in the reaction control system in one of four “doghouse” assemblies mounted on the exterior of the Starliner's drum-shaped service module.
Each doghouse includes four orbital maneuvering and attitude control (OMAC) thrusters and four smaller reaction control system maneuvering jets. Pressurized helium gas is used to push the thrusters in the rocket engines in each pod, as well as four powerful launch abort engines that would only ignite in the event of a catastrophic booster failure.
Engineers tightened the bolts around the flange where the leak was detected, pressurized the lines, and then tested to determine if the leak was still present. Meanwhile, the launch was retargeted to May 21 and then, when tests revealed the leak was still present, to Saturday to give engineers more time to evaluate the data.
The flight is now on hold indefinitely, pending the results of the ongoing analysis.
