Catherine Rusoff
After analyzing data following a launch on Monday, United Launch Alliance managers decided to transport the Atlas 5 rocket carrying Boeing’s Starliner astronaut ferry back to their processing facility to replace a suspected valve, delaying another launch attempt until at least May 17, NASA said in a blog post Tuesday.
The new “no earlier than” launch target of Cape Canaveral Space Force Station in Florida – 6:16 p.m. EDT a week from Friday – will give engineers more time to perform the valve repair while arranging a rendezvous with the International Space Station which falls under the launch schedule of the US Eastern Range, which coordinates all East Coast rocket flights.
United Launch Alliance
The Starliner, Boeing’s long-delayed answer to SpaceX’s Crew Dragon spacecraft, touched down Monday just two hours before its planned launch on its first piloted test flight to the space station. On board were NASA astronauts Barry “Butch” Wilmore and Sunita Williams.
The culprit: a pressure relief valve in the liquid oxygen plumbing of the Centaur rocket’s upper stage that failed to seat properly during the final stages of propellant loading. The valve “vibrated” repeatedly as it tried to seal, rapidly opening and closing so fast that engineers on the launch pad reported an audible buzzing sound.
ULA engineers could have performed a procedure to force the valve into place and likely would have done so for a normal satellite launch. But the conservative flight rules in place for the Starliner flight ruled out any changes to the rocket’s “fueled state” while the astronauts were on board. As a result, the release was eliminated.
The valve in question is designed to “self-regulate,” opening and closing as needed to release the build-up of gaseous oxygen in the Centaur’s liquid oxygen tank. It has been certified for 200,000 opening and closing cycles.
“Valve oscillating behavior during prelaunch operations resulted in mission teams calling for a May 6 launch,” NASA said in a blog post. “After the ground and flight crew safely exited Space Launch Complex-41, the ULA team successfully commanded the valve to close and the oscillations were temporarily damped.
“The oscillations occurred again twice during fuel removal operations. After evaluating the valve’s history, data signatures from the launch attempt, and evaluating the risks relative to continued use, the ULA team determined that the valve exceeded its qualification and mission managers agreed to remove and replace the valve.”
The ULA team plans to transport the Atlas 5 and its mobile launch pad back to the nearby Vertical Integration Center on Wednesday. After the valve is replaced and tested, the rocket will be moved back to the pad for normal pre-launch preparations.
After the space shuttle’s retirement, NASA funded the development of two independently designed, built, and operated crew transport ships, awarding a $4.2 billion contract to Boeing for its Starliner and a $2. .6 billion to SpaceX for the company’s Crew Dragon ferry.
The Starliner is years late after a series of technical problems that cost Boeing more than $1 billion to fix. Meanwhile, SpaceX’s Crew Dragon carried 50 astronauts, cosmonauts and civilians to orbit in 13 flights, 12 of them to the space station.
While Boeing has been under intense scrutiny In recent months, due to problems with its 737 planes, the Starliner program, although delayed, is a separate operation. The launch delay was not the result of any problems with Boeing’s hardware.
