WASHINGTON — Alan Bean uses bits of lunar dust and tiny slices of spacesuit patches to bring the moon closer to people who will never have a chance to go there.

The Apollo 12 moonwalker left NASA 28 years ago to chart a new career as an artist, inspired by his astronaut experience.

On Thursday, the largest exhibit of his work ever mounted, "Alan Bean: Painting Apollo, First Artist on Another World," opened at the National Air and Space Museum — in time for today's 40th anniversary celebration of the first human steps on the moon.

"Half the people on Earth were not around when this was taking place," said Bean, 77. "These paintings will be around long after I'm gone."

They depict some of the most famous moments of Neil Armstrong and Buzz Aldrin, who landed in 1969. Some show lunar landscapes, and the experiments and exploration by the Apollo astronauts. Others capture the boyish wonder of the experience, such as Alan Shepard hitting a golf ball on the moon.

Bean was the lunar module pilot on Apollo 12 in November 1969 for the second moonwalk mission and became the fourth person to set foot on the moon. Memories from that voyage and stories from all six moon landings have gone into his nearly 170 original paintings.

Of those, 43 works are included in the exhibit, which will be on view through January at the Smithsonian Institution museum. The show includes Bean's tools, techniques, and some of the artifacts depicted in his paintings — a lunar rover, a box for moon rocks and a replica of Shepard's golf club.

Bean lights up as he shows off his technique — making boot prints in the texture of his works and mixing pieces of history with the paint.

He never had a moon rock to keep, but he did have patches from his spacesuit that were soiled with moon dust.

"I said to myself, 'If I am willing to cut these things up and put them in the paintings, then I will have moon dust in my paintings,' " he said. "If I'm spending the rest of my life doing this, I might as well make these paintings as fun for me as I can make them."

No one ever complained to Bean about how he was using the traces of moon dust, though some astronaut friends questioned whether it was wise for him to leave all his flight training behind to be an artist. Now, he says, they love his work.

Curator Carolyn Russo said Bean's work encompasses the entire Apollo program.

"He puts himself into his paintings," she said. "To cut up his tiny little patches that came back from the moon — his most precious things — he's giving them back to us in his work.

"You know how they say you can't take it with you? I think Alan understands that," she said.

He critiques his early work, saying he "didn't have the heart of an artist" at first. Now he paints at his Houston studio at least six days a week beginning at 8 a.m., completing about seven paintings a year.

"No matter how good or bad they are, they are the first paintings in all of history of another place that an Earth human has actually seen and painted," Bean said. "When we're all gone, a lot of these stories will be lost."

The exhibit will be the setting for NASA's exclusive party today to celebrate the first moonwalk.

Though decades have passed since Apollo and NASA is debating how it will return humans to the moon, Bean remains bullish on the space program, though it's taking longer than he expected to establish permanent lunar outposts.

"Some day, when they have art galleries on the moon," he said, "they'll put some of these paintings there."

(See some of his paintings at www.alanbeangallery.com/NASMExhib.html.)