The launch of a United Launch Alliance Atlas 5 rocket carrying Boeing's Starliner capsule will be delayed another four days, from Friday to next Tuesday, to give engineers time to make sure a helium leak in the system has been resolved. of the crew's boat, officials said Tuesday.
Liftoff from Pad 41 at Cape Canaveral Space Force Station is now scheduled for May 21 at 4:43 pm EDT, establishing docking at the International Space Station the following afternoon. The flight is expected to conclude with a landing in White Sands, New Mexico, around May 30.
Mission commander Barry “Butch” Wilmore and co-pilot Sunita Williams expected to take off on the Starliner's first piloted flight last Monday. They were in the process of buckling up when the countdown was canceled due to a problem with an oxygen pressure relief valve on the rocket's Centaur upper stage.
Two days later, Atlas 5 was removed from the launch pad and moved back to the nearby ULA Vertical Integration Facility, where the suspect valve was replaced. The tests confirmed that the rocket is ready for another launch attempt.
The unrelated helium leak in the Starliner's booster pressurization system was detected during countdown last week, but remained within safe limits for flight. After the Atlas 5 and Starliner returned to the VIF to replace the oxygen valve, managers decided to take a closer look at the helium issue.
The leak was detected in pipes that form a helium manifold inside one of four “doghouse” assemblies spaced around the exterior of the Starliner's drum-shaped service module. Each doghouse has four Orbital Maneuver and Attitude Control (OMAC) thrusters and four small maneuvering jets with reaction control system.
Pressurized helium gas is used to push propellants to the rocket motors in each doghouse, as well as to four powerful motors at the base of the spacecraft that would be used during an in-flight abort to propel the capsule away from a booster that works bad. The leak was attributed to a flange on a single RCS propeller.
The bolts have been retightened and engineers believe the system is ready to fly. But managers decided to pressurize the helium lines throughout the spacecraft so that engineers can monitor them over time and make sure that, in fact, the lines are leak-free or within acceptable limits.
“As part of the testing, Boeing will bring the propulsion system to flight pressurization just as it does before launch, and then allow the helium system to vent naturally to validate existing data and strengthen flight logic,” the company said in a statement.
“Mission teams have also completed a thorough review of the data from the May 6 launch attempt and are not tracking any other issues.”
Wilmore and Williams, both veteran Navy test pilots and astronauts with four flights to the station between them, flew back to Johnson Space Center in Houston last Friday for additional simulator training. They are expected to return to Florida later this week to prepare for another launch attempt.
The Starliner is one of two commercially acquired crew shuttles commissioned by NASA following the retirement of the shuttle program in 2011. SpaceX won a contract valued at $2.6 billion for the development of the company's Crew Dragon spacecraft and Boeing. received $4.2 billion to develop the Starliner.
The goal was to stimulate the development of commercially operated independent spacecraft capable of transporting astronauts to and from the International Space Station. Ordering spacecraft from different suppliers would allow NASA to continue sending crews to the space station even if a problem grounded a company's ferry.
SpaceX launched its first two-man crew in 2020. Since then, the company has launched eight NASA-sponsored crew rotation flights to the station, three commercial research missions to the lab, and one funded two-man, two-woman trip. private. to low Earth orbit. In total, 50 people have flown into space aboard Crew Dragons.
Wilmore and Williams will be the first astronauts to fly aboard a Starliner after a series of technical failures that included major software problems during an initial pilotless test flight in December 2019 and corroded propulsion system valves that delayed a second uncrewed test mission until May 2022.
The second test flight, paid for by Boeing, was a success, but engineers ran into additional questions about the parachute harness connectors and protective tape wrapped around the wiring that posed a fire hazard in a short circuit. Work to fix those issues and others delayed the first pilot launch until this month.
The Atlas 5 oxygen valve problem was the responsibility of United Launch Alliance. The helium leak responsible for the latest delay is on Starliner's list, but was considered a relatively minor issue. That said, managers spare no effort to ensure flight safety.
