Houston, We Have a Problem: Where Are the Astronauts?

She quickly drove back to Johnson. “I was late,” she said. “Very late.”

Mr. Wiseman was at the doctor’s office. “Like all good doctor’s appointments, this one was going way over,” he said.

He told Mr. Acaba he was going to miss the meeting, but Mr. Acaba said he should join via videoconference. When he did, Mr. Wiseman saw not only Mr. Acaba but also Mr. Glover, Ms. Koch and Norman Knight, NASA’s director of flight operations who is Mr. Acaba’s boss.

“‘I was like, Oh man, this is not the meeting I’m supposed to be missing,’” Mr. Wiseman said.

“We feared that we didn’t show well at that moment,” Ms. Koch said.

And then they found out the news.

“After all the embarrassment,” Mr. Glover said, “they asked us how we felt about being the crew of Artemis II.”

Mr. Wiseman, who was selected as commander of the mission, said, “It wasn’t the greatest start.”

“They were a little bit late,” Mr. Acaba said. “And luckily, I didn’t want to change my mind.”

Mr. Hansen found out more simply, via a phone call from Lisa Campbell, the president of the Canadian Space Agency. “That was a pretty special phone call for me,” Mr. Hansen said. “And then I was permitted to share it with my wife and children as long as they were sworn to secrecy.”

Vjosa Isai contributed reporting.