Astronaut Chris Hadfield has logged 4,000 hours in space. But his career may be defined by the five-minute, 30-second cover of David Bowie’s “Space Oddity” that he filmed in 2013. The cover is so good that Bowie himself sung Hadfield’s praises in a Facebook post, declaring the music video “poignant.”

Since returning to Earth, Hadfield has been making videos of a different sort: education classes for space enthusiasts and aspiring astronauts. Available via MasterClass, an online education company that creates courses taught by celebrity instructors, Hadfield’s video lessons will focus on space exploration.

“It’s a really interesting time in space exploration right now, it’s like the doors just got blown open,” Hadfield says, calling from his summer cottage in southern Ontario. He attributes the renewed interest, in part, to the International Space Station (ISS), of which he served as commander for six months while in orbit. “It’s the most complicated thing we’ve ever built in space and one of the biggest international projects ever attempted by humanity,” he says.

[Photo: courtesy of MasterClass]

While on the ISS, Hadfield and his crew were simultaneously conducting 200 scientific experiments. They studied how flames behave without gravity, as well as how nanoparticles move in fluid without gravity. They tracked temperature and pollution, from above. And they also tested the types of essential systems required for any future trips to the Moon, Mars, and beyond–toilets, for example.

“The course is everything I know and everything I’ve learned,” he says. “It’s for anyone…