Boeing’s Starliner spacecraft returns to processing facility for valve work

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After valve problems caused it to miss an opportunity to launch earlier this month on a test flight to the International Space Station, Boeing’s Starliner crew capsule returned to a processing facility at the Kennedy Space Center Thursday after being removed from its Atlas 5 launcher at nearby Cape Canaveral Space Force Station.

United Launch Alliance detached the Starliner spacecraft from the top of its Atlas 5 rocket Thursday inside the Vertical Integration Facility at Cape Canaveral.

A crane lowered the capsule onto a road transporter to ferry the spaceship back to Boeing’s processing facility near the Vehicle Assembly Building at Kennedy Space Center, where engineers plan to resume troubleshooting stuck valves that prevented the Starliner from launching Aug. 3 on an unpiloted demonstration flight to the space station.

Boeing officials said last week they would give up on fixing the valves while the spacecraft remained on top of its Atlas 5 launcher, a decision prompted by scheduling constraints in the next couple of months, both at the space station and on ULA’s launch manifest at Cape Canaveral.

A SpaceX Dragon cargo capsule is set for launch Aug. 28 from pad 39A Kennedy Space Center with several tons of supplies heading for the space station. The Dragon spacecraft will remain at the station until late September, occupying the same docking port needed by the Starliner spacecraft.

Boeing’s Starliner spacecraft returns to its factory Thursday at the Kennedy Space Center in Florida. Credit: Stephen Clark / Spaceflight Now
Meanwhile, ULA is scheduled to launch a robotic NASA spacecraft named Lucy during a 22-day window opening Oct. 16. The Lucy mission has to get off the ground by early November to take advantage of a unique planetary alignment, permitting the spacecraft to fly by eight asteroids on a tour of the solar system.

If Lucy doesn’t get off the ground during this fall’s launch window, the next opportunity to launch the mission comes in October 2022. After that, the mission would have to be replanned.

Following the removal of the Starliner spacecraft from its Atlas 5 rocket Thursday, ULA plans to detach the launch vehicle’s dual-engine Centaur upper stage and two solid rocket boosters. The Atlas 5’s main stage will remain on the launch platform for use on the Lucy mission.

ULA will stack a different Centaur upper stage with a single RL10 engine for the Lucy mission, which doesn’t require any solid-fueled rocket motors for an additional boost.

With a busy Atlas 5 launch schedule in Florida and numerous crew and cargo ships heading to the space station, the return of the Starliner spacecraft to Boeing’s factory delays the test flight’s launch until at least late this year, and perhaps into 2022.

Boeing said last week that it “recovered” all but four of the troublesome valves in the Starliner propulsion system. But time ran out as the mission faced a deadline of Aug. 20 to launch or else wait for another slot in the Atlas 5 and space station schedules.

The problem first appeared as Boeing and ULA prepared for a launch attempt Aug. 3, when 13 valves in the Starliner’s service module failed to budge during a pre-launch checkout.

Boeing’s Starliner spacecraft returns to its factory Thursday at the Kennedy Space Center in Florida. Credit: Stephen Clark / Spaceflight Now
The Starliner’s service module has 28 reaction control system thrusters, each generating about 85 pounds of thrust. The service module has 20 more powerful orbital maneuvering and attitude control thrusters providing 1,500 pounds of thrust. There are four large launch abort engines at the base fo the spacecraft, each with 40,000 pounds of thrust. Those would only be activated in the event of an emergency during launch.

There are 12 control thrusters on the reusable Starliner crew module. The service module is disposable and used only once.

The service module thrusters are all fed by hydrazine fuel and nitrogen tetroxide oxidizer. When the liquids make contact, they automatically ignite.

Boeing said the service module has 24 fuel valves and 24 oxidizer valves to control the flow of propellant to the thrusters. There are an additional 16 valves in helium lines used to pressurize the propulsion system.

All 13 troublesome valves are associated with the oxidizer system. After inspections and troubleshooting inside the VIF, Boeing technicians got nine of the valves to move into the correct positions.

John Vollmer, manager of Boeing’s Starliner program, said last week that engineers believe atmospheric moisture made its way into the service module. The moisture apparently reacted with the nitrogen tetroxide to create nitric acid, which corroded the valves and caused them to stick, Vollmer said.

Boeing said it was too early to know whether the valves might need to be redesigned, or whether ground teams could take more steps to ensure moisture does not get into the valves.

Boeing’s Starliner spacecraft returns to its factory Thursday at the Kennedy Space Center in Florida. Credit: Stephen Clark / Spaceflight Now
Boeing’s commercial crew capsule was poised to head into orbit on a five-day test flight to the International Space Station. The mission — called Orbital Flight Test-2 — is a do-over of a problem-plagued test flight in 2019 that failed to reach the space station due to software errors.

If Boeing’s second shot at the unpiloted test flight goes well — whenever it happens — it will pave the way for the next Starliner mission to carry three astronauts to the space station.

Before the valve problem, Boeing hoped to launch the first crew on a Starliner test flight by the end of this year. That is now surely delayed into 2022.

Once the Orbital Flight Test and Crew Flight Test are complete, NASA will clear the Starliner spacecraft to begin carrying astronauts to and from the space station on at least six operational crew rotation flights.

NASA has multibillion-dollar commercial crew contracts with Boeing and SpaceX for astronaut transport services. SpaceX launched its first crew test flight in May 2020, and has already launched its first two operational crew rotation missions to the space station, with a third set for liftoff Oct. 31.,50478585.html,50478549.html

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