For the second time in a month, the first crewed launch of Boeing’s Starliner space capsule to the International Space Station was called off while the crew members were in their seats, waiting for liftoff.
The hold was automatically triggered by the launch-pad computer system that manages the final minutes of the countdown for Starliner’s launch vehicle, an Atlas V rocket provided by United Launch Alliance.
The ground launch sequencer forced an end to today’s launch attempt at Cape Canaveral Space Force Station in Florida with just three minutes and 50 seconds remaining in the countdown. Mission managers started investigating what triggered the alarm even as the launch pad team began the process of helping NASA astronauts Butch Wilmore and Sunita Williams out of the capsule.
United Launch Alliance CEO Tory Bruno said the automated launch sequencer triggered an alarm because a circuit card on one of three redundant computer racks came up about six seconds more slowly than the other two. That particular card controls activities that free up the rocket for liftoff.
“For that system, we do require all three systems to be running. … Two came up normally. The third one came up, but it was slow to come up,” Bruno said at a news briefing. “That tripped a red line that created an automatic hold.”
The NASA-ULA-Boeing team said it would pass up a launch opportunity on Sunday to give engineers more time to assess the situation. The computer problem could be due to faulty hardware, which would be relatively simple to swap out, or it could be a more complex issue involving network connections between the computers. Update: Engineers identified and replaced a faulty ground power supply. Details at the end of this report.
Mission managers had to deal with other issues during today’s countdown: A data glitch caused problems for the valves that are used to top off the propellant tanks on the Atlas V rocket’s Centaur upper stage. That glitch was resolved by switching over to a backup system. About 15 minutes before the scheduled launch time, the air-circulating fans in the astronauts’ spacesuits malfunctioned. Resetting the fans fixed the problem.
The next opportunity for liftoff will come on Wednesday.
Starliner is due to transport Wilmore and Williams on a shakedown cruise to the International Space Station — a trip that’s also meant to deliver supplies and a replacement pump for the station’s urine-recycling system. The gumdrop-shaped capsule has been through two uncrewed test flights, but this mission will mark the first time Starliner carries astronauts to orbit.
Today’s scrub marked the latest setback for a development and testing effort that has already been through years of delays — and more than $1 billion in cost overruns that Boeing has had to cover.
Starliner’s first uncrewed flight test fell short of full success in 2019, forcing a second uncrewed test that met its objectives in 2022.
A fresh set of problems cropped up during the first attempt to launch the crewed flight test on May 6. Mission managers called off that countdown two hours before launch, due to a balky oxygen relief valve on the rocket’s Centaur upper stage. In the course of resolving that issue, engineers detected a small helium leak that was traced to a flange on one of the Starliner service module’s thrusters.
NASA and Boeing spent days assessing the leak’s potential impact, and the team decided the safest course of action was to live with the leak and work around it.
Engineers also learned of a potential design vulnerability in Starliner’s propulsion system — an issue that could hamper the capsule’s ability to execute a deorbit burn if two of the four thruster units known as “doghouses” were to fail at the same time.
The mission team developed a work-around for the crewed flight test. After that mission is complete, NASA and Boeing will take a closer look at the propulsion system design, and at the leaky helium pressurization system.
Yet another concern came to light at the end of a crewed suborbital space mission that was conducted by Jeff Bezos’ Blue Origin space venture on May 19. When the New Shepard crew capsule descended toward touchdown, one of its three parachutes failed to open completely. Starliner’s parachute system uses a similar design, so NASA and Boeing worked with Blue Origin to make sure the problem wouldn’t crop up during the orbital test mission.
Steve Stich, program manager for NASA’s Commercial Crew Program, said Blue Origin traced the parachute problem to a reefing line that’s designed to keep the parachute from opening prematurely. There’s a mechanism that’s supposed to cut the line at the proper moment, but Stich said “the cutters, for some reason, did not cut that line.”
“We use a very similar cutter to what Blue Origin uses, so it was important for us to look at that data,” Stich said. “We went back and looked at all of our test data.” Stich said the Starliner system’s cutters had been successfully tested 160 times, which reassured the team that the parachutes were good to go.
NASA made a last-minute switch in the payloads for Starliner’s flight test: The pump for the space station’s urine-recycling system failed unexpectedly, forcing the crew to store their urine in bags and tanks. NASA decided to provide some relief, so to speak, by sending up a 150-pound replacement tank in Boeing’s capsule.
To keep Starliner’s mass distribution in balance, two suitcases containing clothing and personal hygiene items for Wilmore and Williams were removed from the payload manifest. “They’ll just use our generic supplies that we have on board,” said Dana Weigel, who manages NASA’s International Space Station Program. “The reason why we have them there is for cases like this.”
If everything goes according to plan, Wilmore and Williams will spend about eight days on the space station. At the end of their space station stay, the duo will ride Starliner back down for a parachute-aided, airbag-cushioned landing in the western U.S., at a site to be determined based on the weather and the timing of the return.
Boeing will use the data gathered during the test flight to fine-tune its spacecraft design. Those refinements should clear the way for Starliner to take its place alongside SpaceX’s Crew Dragon as a commercial “space taxi” that’s capable of ferrying astronauts to and from orbit.
Mission managers said they were disappointed that today’s launch had to be scrubbed in the final minutes of the countdown, but they shifted their focus to the next launch attempt. Mark Nappi, vice president and program manager of Boeing’s Commercial Crew Program, compared the situation to a baseball game.
“When you’re playing a game, and you get a bad call, you’re a little irritated at first, a little frustrated at first. But you immediately focus on the next pitch, and that’s what our teams do. They’re focused on the next pitch,” Nappi said. “The team’s professional. They just work to the next play.”
Update for 5 p.m. PT June 2: In a mission update, NASA said United Launch Alliance’s technicians and engineers identified an issue with a single ground power supply that provides power to a subset of computer cards in one of the three control racks. The power unit was replaced, and all hardware is performing normally, NASA said. The next launch attempt is now set for 10:52 a.m. ET (7:52 a.m. PT) on Wednesday.
