Going to outer space is serious business. Astronauts work long hours completing research, keeping things clean, performing maintenance, and much more. Even when the astronauts have some downtime, their options are pretty limited.

So, to fill the hours when they aren’t working, astronauts sometimes try to come up with some fun and interesting things to do. Some of them will read, others engage in amazing photography, and then some try to pull pranks.

One of the most epic pranks in space history took place way back in 1973. This was long before the International Space Station was launched, and it took place on NASA’s Skylab space station.

Astronaut Owen Garriott was on the Skylab 3 mission (which, oddly, was actually the second mission on this space station).

The mission began on July 28, 1973, and Garriott was slated to be on the station for about two months. Near the end of the mission, he put his prank into action. Garriott told the story to NASA on their Oral History project:

As Skylab comes around in orbit to get into radio communication, all of a sudden this female voice comes on the line, and says, “Hello, Houston, this is Skylab.

The capcom, who happened to be Robert [L.] Crippen, said, “Well, hello, Skylab. Who is this?”

This female voice says, “Hi, there, Bob, this is Helen,” my wife at the time.

“What are you doing up there?” Crippen asks.

“Well, we just came up to bring the boys a fresh meal, or a hot cooked meal. They haven’t had one for quite a while. We thought they might enjoy that.”

He says, “How did you get there?”

 She says, “Oh, we just flew up. We’ve been looking at those forest fires that they have all over California. It’s a beautiful site from up here.” The female voices says, “Well, I see the boys are floating in my direction. I’ve got to get off the line. I’m not supposed to be talking to you. See you later, Bob,” and then it goes off.

Garriott explains the full story in this video:

While the folks on the ground at NASA knew that it was impossible for his wife to travel up to the space station, they had no idea how it was done. They couldn’t, however, figure out how he pulled it off.

In 1998, Garriott explained the prank to NASA, who were kept in the dark for over 25 years.

While not the only prank ever to take place in space, it is certainly one of the best.

If you found that story interesting, learn more about why people often wake up around 3 AM and keep doing it for life.