by The launch of the United Launch Alliance Atlas 5 rocket carrying Boeing’s hard-luck capsule has been delayed another four days, from Friday to next Tuesday, to ensure that leaks are contained. little helium in the propulsion system of the crew ship resolved. , officials said Tuesday.
Liftoff from pad 41 at the Space Force Station Cape Canaveral is now targeted for 4:43 pm EDT May 21, establishing a dock at the International Space Station the following evening. The flight is expected to end with a landing in White Sands, New Mexico, around May 30.
Mission commander Barry “Butch” Wilmore and co-pilot Sunita Williams hoped to get out of the Starliner’s first pilot flight last Monday. They were strapping in when the countdown was stopped due to a problem with an oxygen pressure relief valve in the upper stage of the Centaur rocket.
Two days later, the Atlas 5 was towed off the launch pad and back to the nearby ULA Vertical Integration Facility, where the suspect valve was replaced. Tests confirmed that the rocket is good enough to attempt another launch.
The unrelated helium leak in the Starliner’s propellant pressurization system was noted during last week’s countdown, but remained within safe flight limits. After rolling the Atlas 5 and Starliner back to the VIF for oxygen valve replacement, managers decided to take a closer look at the helium issue.
The leak was detected in a distribution manifold inside one of four “doghouse” assemblies spaced around the outside of the Starliner’s drum-shaped service module. In each doghouse there are four orbital maneuvering and attitude control – OMAC – thrusters and four mini-maneuvering reaction control system jets.
Pressurized helium gas is used to push propellants to the rocket motors in each doghouse. The leak was traced to a flange on one RCS thruster.
Bolts have been reset and engineers believe the system is ready for flight. But managers decided to pressurize the helium lines throughout the spacecraft to ensure that the lines are, in fact, leak-free or within acceptable limits.
“As part of the test, Boeing will bring the propulsion system up to flight pressure just as it does before launch, and then allow the helium system to vent naturally to validate the existing data and strengthen the flight rationale ,” the company said in its 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, veteran Navy test pilots and astronauts with four flights to the station between them, flew back to the Johnson Space Center in Houston last Friday for additional simulator training. They are expected to fly back to Florida late this week to prepare for another launch attempt.
The Starliner is one of two commercially built crew ferry ships ordered by NASA after the shuttle program was discontinued in 2011. SpaceX won a $2.6 billion contract to develop the company’s Crew Dragon spacecraft and Boeing was awarded $4.2 billion to develop the spacecraft. Star line.
The goal was to encourage the development of commercially operated independent spacecraft capable of transporting astronauts to and from the International Space Station. Spacecraft from multiple vendors will allow NASA to continue sending crews to the space station even if one company’s ship experiences a problem.
SpaceX launched its first two-man crew in 2020. Since then, the company has launched eight crewed rotation flights to the station sponsored by NASA, three commercial research missions to the laboratory and a two-man, two-woman trip, privately funded. 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 Starliner after a series of technical glitches that included major software problems. during an initial unpiloted test flight in December 2019 and corroded propulsion system valves delayed the second uncrewed test mission to May 2022.
The second test flight was successful, but engineers raised further questions about parachute harness connectors and protective tape wrapped around wiring that created a short-circuit fire hazard. Work to correct those and other issues delayed the first pilot launch until this month.
Atlas 5’s oxygen valve problem was the responsibility of United Launch Alliance. The helium leak responsible for the latest delay goes on the Starliner list, but it appears to be a relatively minor problem and would not have prevented last week’s launch.
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