Moon dust collected by Neil Armstrong during the first moon landing in 1969 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 expected to fetch up to an estimated $4 million (£3m).
Sotheby's New York is holding the auction to mark the 48th anniversary of the first lunar landing on July 20.
"The only such relic available for private ownership, it is exceptionally rare," Sotheby's said on its website.
During the Apollo 11 mission, Armstrong collected nearly 500 grams of material finer than one centimetre.
He also collected 12 rock fragments from five different locations on the lunar surface in the region known as the Sea of Tranquillity.
The auction house will put the bag on display during a virtual reality conference on July 13 ahead of the auction.
Armstrong died in 2012 at the age of 82 in Ohio.
Also being sold is Armstrong's snapshot of fellow Apollo 11 astronaut Buzz Aldrin standing on the moon which could be sold for up to $4,000.
The auction is open to the public and those that are interested in bidding will be expected to register in advance.