At the end of 2019, Boeing appeared to have a good chance of beating SpaceX to become the first private American company to take astronauts into orbit.
A lot has gone wrong in those four and a half years. Here’s a timeline of the failures that have put Boeing so far behind SpaceX in providing American astronauts a ride into low Earth orbit.
December 2019: “High Visibility Challenge”.
On December 20, 2019, Boeing appeared to be at home.
The Starliner capsule — the same spacecraft expected to carry NASA astronauts Butch Wilmore and Suni Williams to the space station on Saturday — was on the launch pad atop an Atlas V rocket.
The test flight to the space station had no astronauts on board and was designed to assess the spacecraft’s navigation, propulsion and docking systems. If the flight passes this final technical hurdle, a trip with astronauts on board could take place within months.
The Atlas V rocket launched flawlessly and launched the Starliner.
And then the mission immediately went awry.
The spacecraft’s clock was set to the wrong time, so the Starliner thought it was in the wrong place. The capsule fired its jets to try and get to where it thought it should be. At the same time, the communication glitch frustrated the efforts of flight controllers in mission control to diagnose and correct the problem.
The Starliner spacecraft had consumed too much propellant and the planned docking with the space station was called off.
During troubleshooting, Boeing engineers discovered another software bug that would fire the wrong jets during the reentry maneuver. NASA called the incident a “high-visibility search call” that could have destroyed the spacecraft if the errors weren’t corrected from the ground during the flight.
The investigation revealed numerous failures of Boeing’s processes that should have caught the errors before takeoff. The exhaustive audit reviewed one million lines of software code.
NASA officials admitted they may have placed too much faith in Boeing, which had decades of experience working with NASA.
Summer 2021: Corrosion on the launch pad.
NASA and the company decided that a second unmanned test was needed before flying with astronauts on board. The spacecraft was launched onto the launch pad in July, but a problem aboard the space station prompted a delay to early August. Then, before the Aug. 4 launch attempt, mission managers discovered corroded propellant valves on the Starliner that would not open. The test flight was called off and another lengthy round of troubleshooting ensued.
May 2022: Another launch, more problems.
The second unmanned test was finally launched on 19 May 2022.
During the maneuver to get the Starliner into a stable orbit, two thrusters failed, but the spacecraft was able to compensate. It continued to dock with the space station and successfully returned to Earth.
July 2023: Parachutes and tape.
Before the test flight with astronauts on board, which was then planned for July 2023, two more problems arose. The protective tape that was wrapped around the wiring insulation proved to be flammable, and a key part of the parachute system was weaker than designed and could rupture if the Starliner’s three parachutes failed to deploy properly.
About a mile of webbing was replaced and the parachute structure was upgraded and strengthened and then retested.
May 2024: Still not ready to fly.
“We’ve taken our time to go through everything methodically because it’s a test flight, and we want it to go well,” Steve Stich, program manager for NASA’s Commercial Crew Program, said during a May 3 news conference.
Mark Nappi, Boeing’s program manager for the Starliner, said: “We are ready to do a test flight. And I’ve never felt more prepared for any mission I’ve ever been on.”
But the Starliner was still not quite ready.
The May 6 countdown was going smoothly until a noisy valve on the Atlas V rocket’s second stage — unrelated to the Starliner — began to lift and audibly vibrate about 40 times per second.
The launch was called off and the rocket had to be removed from the launch pad to replace the valve. This work was completed within a few days.
But a more pressing problem arose.
As the propellants were released from the Atlas V rocket’s tanks, engineers discovered a small leak of helium in the Starliner’s propulsion system.
Helium, an inert gas, is used to push propellants into the jets, and if too much helium is lost, the jets may not function properly.
The leak was traced to a seal on a helium line leading to one of 28 small nozzles known as reaction control system engines.
“Just like you would have a faucet or something like that on any piece of your plumbing at home,” Mr. Stich said during a May 24 telephone news conference. “There’s a seal that holds that interface tight.
Tests showed no leaks in the seals leading to the other 27 engines of the reaction control system, and engineers were confident that a single leak was manageable. There are no plans to replace the seals, which would require removing the Starliner from the Atlas V rocket and lead to even longer flight delays.
“We could handle this particular leak if the number of leaks increased even up to 100 times,” Mr. Stich said.
The helium leak led NASA and Boeing to take a closer look at the Starliner’s propulsion system, which revealed a “structural vulnerability,” Mr. Stich said. If a series of unlikely failures occurred, the spacecraft might not be able to deliver the astronauts safely back to Earth.
If there were problems with the larger engines to be fired during the deorbit maneuver, one of the backup plans was to use eight smaller thrusters. However, the analysis showed that another failure could mean that only four smaller jets would be available.
Engineers then developed another backup plan to get the Starliner out of orbit with only four thrusters. NASA and Boeing officials said that after weeks of studying the problem, they were confident they could resolve the problems that might arise from the leak.
And on Saturday, Mr. Wilmore and Mrs. Williams may finally fly on the Starliner.