After analyzing data following a launch check Monday, United Launch Alliance managers decided to transport the Atlas 5 rocket carrying Boeing's Starliner astronaut ferry to its processing facility for replacement a suspect valve. delay another launch attempt at least until May 17, NASA said in a blog post Tuesday.
The new “no sooner” launch target from Florida's Cape Canaveral Space Force Station — 6:16 p.m. EDT a week from Friday — will give engineers more time to carry out the valve repair while a rendezvous with the International Space Station is arranged. which conforms to the US Eastern Range launch schedule, which coordinates all rocket flights from the East Coast.
United Launch Alliance
The Starliner, Boeing's long-delayed answer to SpaceX's Crew Dragon spacecraft, touched down Monday just two hours before its scheduled launch on its first manned 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 pipe of the Centaur rocket's upper stage that failed to seat properly during the final stages of propellant loading. The valve “chattered” repeatedly as it tried to seal, opening and closing rapidly, so launch pad engineers reported an audible hum.
ULA engineers could have performed a procedure to force the valve into place and probably 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 “fuel status” while the astronauts were on board. As a result, the launch was cleaned up.
The valve in question was designed to be “self-regulating,” opening and closing as needed to remove buildups of gaseous oxygen in the Centaur's liquid oxygen tank. It was certified for 200,000 opening and closing cycles.
“The oscillating behavior of the valve during pre-launch operations resulted in mission teams calling in a launch jam on May 6,” 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 dampened.
“The oscillations re-occurred twice during defueling operations. After evaluating the valve history, data signatures from the launch attempt, and assessing the risks related to the “continued use, the ULA team determined that the valve exceeded its rating, and mission managers agreed to remove and replace the valve.”
The ULA team plans to transport Atlas 5 and its mobile launch pad back to the nearby Vertical Integration Facility on Wednesday. After the valve is replaced and tested, the rocket will be moved back to the pad for normal pre-launch preparations.
Following the retirement of the Space Shuttle, NASA funded the development of two independently designed, built and operated crew transport vehicles, awarding a $4.2 billion contract to Boeing for its Starliner and a $2.6 billion contract of dollars to SpaceX for the company's Crew Dragon shuttle.
The Starliner years behind schedule after a series of technical problems that have cost Boeing more than a billion dollars to correct. Meanwhile, SpaceX's Crew Dragon has carried 50 astronauts, cosmonauts and civilians into orbit on 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 airliners, the Starliner program, although delayed, is an independent operation. The launch delay was not the result of any problems with Boeing's hardware.
