Bean decided to make the switch from astronaut to artist a dozen years after the Apollo 12 mission that took him to the moon in November 1969 and after spending two months in space in 1973 on board Skylab, and his souvenirs from both missions dominate his artwork.

When, at age 49, he dropped a bombshell on his bosses and colleagues at NASA, telling them that he was leaving to become a full-time painter, they wondered if he wasn't in the throes of lunacy.

"My boss could have fallen off the wall," Bean told AFP at the Air and Space Museum in Washington, where his paintings of space went on display in the days leading up to the 40th anniversary of the first lunar landing.

"He asked if I could make a living at painting. My friends thought I was having a midlife crisis," he said.

But they've all come round and now quite like the canvasses that Bean sells for up to 200,000 dollars these days, some incorporating precious moon dust and threads from the American flag that was on his space suit during his moon flight into the textured acrylics that are his preferred medium.

He's parsimonious with his use of his lunar souvenirs; Bean wants them to last as long as he is able to create his works of art.

"If you look at my American flag, it doesn't have any stripes now. They've all been used in paintings," he said.

"I have to somehow stretch these to last as long as I keep painting," he added of the rest of his lunar souvenirs.

Bean's paintings depict not only his own experiences in space but also those of other astronauts.

Since he left NASA 28 years ago, Bean has spent entire days in his studio, crafting his art, which he lays down on wood, not canvas.

One painting takes him nearly three months to complete.

Part of the uniqueness of the 160 paintings Bean has created comes from the fact that the astronaut-artist carves the footprint of a moonboot into a base layer of each work. He does this preparatory carving work with a rockhammer that he used on the moon.

His realist paintings show astronauts in cumbersome spacesuits; Earth, another astronaut, the American flag or the black of space reflecting in their visor as they cavort on the lunar surface like children.

Bean says his paintings are some of the first paintings of a new world, the world of space, and compares them to cave drawings found on Earth.

"Maybe some of these painting will end up on permanent display when they have an art gallery on the moon," he said.

"It may be 500 years from now, but they will have a gallery on the moon," he said.

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