Suni Williams and Butch Wilmore thought they were taking off for a couple weeks in space. Their mission was to test Boeing’s new Starliner spacecraft and then head home. It didn’t go as planned. Nine months later, the NASA astronauts will finally return to Earth from the International Space Station next week if there are no other hitches.

Their relief is scheduled to launch on a SpaceX ship tonight (though weather may change the plan) and arrive at the space station on Saturday. In today’s newsletter, I’ll explain how Williams and Wilmore got stuck in orbit for so long — and why NASA decided not to bring them back sooner.

The saga started in June. Although NASA thought the mission would be short, the agency was careful; it trained Williams and Wilmore to work and live on the space station for months, just in case the flight went awry.

As Starliner approached the space station, some of its thrusters stopped working for a while. Still, it was able to dock. After a couple of months of troubleshooting, space agency officials decided to play it safe. They’d bring Starliner back to Earth without the astronauts. (It landed without incident in September.) But that meant Williams and Wilmore needed another ride home. Think of it as the space version of rebooking passengers after a flight cancellation.

It’s not easy being a NASA travel agent. The agency likes having seven astronauts on the space station. Every six months or so, it swaps four out. (Russia sends three astronauts at a time.) With Williams and Wilmore sticking around, NASA had two more bodies to worry about.

NASA had three choices:

  • Put Williams and Wilmore on the four-seat SpaceX craft that was already docked at the station and bring them home when the other crew’s mission concluded. But that would have meant delaying the return of two of the astronauts who were already there, stretching their stay to about a year.

  • Launch a SpaceX ship to bring home Williams and Wilmore immediately. But with the other SpaceX craft and its four astronauts also departing at about the same time, that would have left the space station understaffed with just three astronauts. Rushing to send replacement astronauts might have cost hundreds of millions of extra dollars and scrambled the schedule for future crew rotations.

  • Launch the next SpaceX mission in September with two astronauts instead of four. Then Williams and Wilmore could stay as part of the space station crew until February, and there would be seats for them on the return trip. Nine months is not an inordinately long time to spend in orbit. Some astronauts have spent a year or longer at the space station.

NASA picked No. 3, though the February pickup date slipped to March as SpaceX failed to ready a new ship on time.

The astronauts have spent their time at the space station on research, mostly studying what the absence of gravity does to the human body. Weightlessness reduces the density of bones. Astronauts counteract that by exercising for a couple of hours a day. Other experiments have looked for changes in eyesight, cardiac health and brain function.

In January, President Trump and Elon Musk opened up a new debate about NASA’s plans. They accused the Biden administration of having callously abandoned Williams and Wilmore. Now the president asked Musk to go rescue them as soon as possible. Musk later added that he had offered to bring the astronauts home months earlier but that NASA had turned him down to avoid helping a Trump ally.

But it’s unknown whom Musk spoke to or what exactly he offered. Musk avoids talking to reporters, and NASA officials have sidestepped questions about him. They say they chose the plan that made the most sense.

To many, an unexpected nine-month layover in orbit sounds like a business trip gone horribly wrong. But astronauts live to go to space, and they don’t get many chances. Williams, 59, and Wilmore, 62, had each been there only twice during a quarter-century at NASA.

In an appearance on “The Daily” today, Williams turned wistful about how this could be her last trip off the planet. “It makes you really want to enjoy every bit of your time that you have up here,” she said.

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