NEW YORK (AP) — Moon dust collected by Neil Armstrong during the first lunar landing is being sold at a New York auction.

The lunar dust plus some tiny rocks that Armstrong also collected are zipped up in a small bag and are worth an estimated $2 million to $4 million.

They’re just some of the items linked to space travel that Sotheby’s is auctioning off to mark the 48th anniversary of the first lunar landing on July 20.

Armstrong’s snapshot of fellow Apollo 11 astronaut “Buzz” Aldrin standing on the moon could go for up to $4,000. Also on the block, is a documented flight plan that astronauts used to return to Earth.

Armstrong was the first man to walk on the moon. He died in 2012 in Ohio.