The Boeing Starliner spacecraft was launched minutes before liftoff

At a news conference shortly after the mission was abandoned on Saturday, ULA CEO Torey Bruno said one of three computer systems that orchestrates the launch sequence in the final minutes of the countdown — by releasing the clamps that hold the rocket in place, for example — Internet access was slow. As a result, the automated system terminated the countdown. ULA is a joint venture between Boeing and Lockheed Martin.

Boeing was eager to launch the mission. It will send NASA astronauts Sunita Williams and Butch Wilmore to the International Space Station for about a week to test how the spacecraft works with humans on board.

“I know it's a little disappointing,” Steve Stich, who heads NASA's Commercial Crew Program, said of the delay. “We were all excited, and Butch and Sonny were excited to fly. That's the way spaceflight works… Every time you go to the manned flight deck or really any flight, you have a chance to clean up.

He added: “You can see today how close we are. We're really close to having this capability ready to go. “We were three minutes and 50 seconds away, and the Starliner spacecraft was ready for launch.”

Due to the fact that the spacecraft has never flown with people on board, NASA and Boeing teams have repeatedly stated that they will proceed with caution and not attempt to fly the mission until they feel they can do so safely.

The flight test with a crew on board was initially scheduled for May 6. But that flight was delayed due to a faulty valve in the rocket's second stage. The valve has since been replaced and officials said it was working fine on Saturday.

The launch is part of NASA's Commercial Crew Program, which has outsourced transportation to the space station to Boeing and SpaceX.

SpaceX has become the dominant manufacturer of commercial rockets and spacecraft; It flew astronauts first, completing its first crewed test mission in May 2020. That flight was a major coup for NASA because it gave it a way to transport crews into space. In 2011, the space shuttle was retired, forcing NASA to rely on Russia to ferry people to the station until SpaceX could begin flying.

The Boeing Starliner has faced setbacks and delays. It had to make two test flights without a crew on board, instead of one flight as expected. The first, in late 2019, was cut short because the rocket's onboard computer was shut down for 11 hours and the spacecraft never reached the station. It reached the space station on the next attempt, in 2022. But the company then discovered that the tape used to cover the capsule's electrical wires was flammable and that its parachutes needed to be upgraded.

Before Saturday's flight, Boeing and NASA officials expressed confidence, saying they had done everything in their power to ensure the mission's success.