Once almost thrown in the trash, the bag used to bring back the first samples of the moon was displayed on Thursday at Sotheby's New York auction house, a week before it goes under the hammer.

The bag is valued at $2 million to $4 million (1.75 million to 3.5 million euros) and is the only artifact from the historic Apollo 11 mission that is allowed in private hands.

US astronaut Neil Armstrong, the first human to walk on the surface of the moon, used the bag to collect samples of lunar dust and moon rock. He died in his home state of Ohio in 2012.

"It's a tremendously rare thing," says Cassandra Hatton, vice president and senior specialist in charge of the sale. "Something that was used by the first man, on the first mission to collect the first samples, it's remarkable."

Sotheby's will hold its "Space Exploration" auction on July 20, the 48th anniversary of the first moon landing by the Apollo 11 crew, which included Armstrong, Michael Collins, and Buzz Aldrin.

Organizers are hoping that the range of space memorabilia will draw large crowds to the auction.

The long journey to the auction block

Armstrong's long-lost bag has had an eventful journey since returning back to planet Earth. All other items from the Apollo 11 mission were sent to the Smithsonian Museum, but the lunar sample bag was misidentified and almost thrown out.

It resurfaced in the garage of a man who managed a museum in Kansas and was convicted of stealing the bag in 2014. The US Marshals Service seized the lunar bag and put it up for auction three times, failing to draw bids until it was purchased in 2015.

A Chicago attorney bought the bag for $995 and sent it to NASA for testing. The US space agency then kept the bag, prompting a legal tussle after which a federal judge granted the owner full rights over the historical artifact.

Other items of space memorabilia on offer include Armstrong's snapshot of Aldrin standing on the moon - expected to fetch between $3,000 to $5,000 - and Apollo 11's flight plan that the astronauts used to return to Earth.

A 1962 space suit that helped pave the way for the Apollo mission moonwalks is also up for sale.

'Magnificent picture'

The Sotheby's auction doesn't only include items from NASA missions, but also from other historic moments in space travel history.

A report from Soviet cosmonaut Yuri Gagarin, who became the first human in outer space in April 1961, will also go under the hammer. Gagarin's description of planet Earth - translated from Russian - is estimated to be worth tens of thousands of dollars.

He described the view from his space craft as a "magnificent picture."

"It [space] is one of few subjects that I think are not culturally specific. It doesn't matter your religion, where you're from, what language you speak," Hatton said. "We all have the common experience of staring up at the sky and wondering what's going on amongst the stars."

rs/msh (AP, AFP, Reuters)