Boeing was supposed to start flying astronauts for NASA 2 years ago. Now its glitching spaceship may not do so until 2023.

• Boeing may not fly astronauts for NASA until 2023 – more than three years behind schedule.
• Boeing's Starliner spaceship is grounded for the rest of the year due to hardware issues.
• Starliner must fly to the International Space Station without a crew before it can launch humans.

Boeing may not fly astronauts for NASA until 2023 – more than three years after it was originally scheduled to do so.

Technical issues and delays have beset Boeing's spaceship development for years. Now, new hardware issues have grounded the company's Starliner spaceship for the rest of this year. It still has to complete an uncrewed test flight to and from the International Space Station (ISS) to show NASA that it can safely carry people.

Starliner won't be ready to make that uncrewed flight until the first half of 2022, Boeing and NASA officials said in a press conference on Tuesday. Only after that can the spaceship fly its first astronauts.

John Vollmer, Boeing's vice president and program manager for Starliner, said that Boeing could "maybe" launch a test flight with an astronaut crew by the end of 2022.

"We like to see six months between flights," he said in a press conference on Tuesday. "Something on that order."

That could easily push the crewed launch into 2023.

Even after fixing the hardware issues and flying the uncrewed test flight, Boeing will still have to analyze data from that mission and complete a series of certification reports and tests. It also has to plan around other missions to the ISS, which don't leave much room open on the station until winter 2022.

Preparations between one flight and the next could take much longer than six months. SpaceX didn't fly its first astronauts for NASA until more than a year after its uncrewed test flight. Now SpaceX is preparing to launch its fourth crew to the ISS, while Starliner sits grounded and nearly three years behind schedule.

Moisture interacted with the spaceship's propellant to corrode its valves

Boeing has tried and failed to reach the ISS twice.

The Starliner spaceship actually launched into orbit in 2019, but it was forced to land without docking to the space station after software issues caused it to burn through its fuel. It took 18 months to investigate that error, fix it, and prepare for another attempt.

Starliner was finally set to lift off for a re-do test flight on August 3, but Boeing had to scrub the launch when it discovered that 13 valves on the propulsion system weren't opening as they were supposed to.

After rolling the spaceship back to the factory and spending two months troubleshooting, Boeing engineers think they've identified the cause of the new hardware issue. Moisture in the air seems to have collected inside the valves, then reacted with the spaceship's dinitrogen tetroxide propellant to form nitric acid, which corroded the valves and made them stick when they were supposed to open.

Now Boeing engineers have to confirm their suspicions by running a few of the valves through a CT scan and disassembling them. Then they have make a few minor changes to prevent moisture from building up inside the valves again.

"This is obviously a disappointing day," Kathy Lueders, associate administrator of NASA's human-spaceflight directorate, said in an August press conference, once it became clear that Boeing would not fly anytime soon. "But I want to emphasize that this is another example of why these demo missions are so very important to us. We use these demo missions to make sure we have the system wrung out, before we put our crews on these vehicles."

Boeing's 3-year delay pushed two astronauts over to SpaceX

This is one of many issues that have hampered both Boeing and SpaceX on the road to flying astronauts. Both companies developed their spaceships through NASA's Commercial Crew Program. NASA originally asked them to provide all the evidence needed to certify their flight systems by 2017, according to a 2018 report by the Government Accountability Office.

Both launch systems were running behind schedule, though. An uncrewed SpaceX Falcon 9 rocket exploded on the launchpad in 2016. Boeing discovered a fuel leak on its spaceship in 2018.

That year, NASA selected astronauts for the spaceships' first crewed flights, announcing that Boeing would fly its first astronauts in 2019.

But software and hardware issues have delayed Boeing's spaceship so much that NASA recently reassigned two astronauts from future Starliner missions to SpaceX's sixth crewed mission. They're now scheduled to launch next fall.