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On the 48th anniversary of humanity's first steps on the moon, the bag of lunar dust collected by Neil Armstrong has sold for $1.8 million.

The Lunar Sample Return Bag used by Neil Armstrong was auctioned for $1.8 million Thursday at Sotheby's in New York City. Sotheby's via EPA

Most of the equipment used in the Apollo 11 mission is kept at the Smithsonian's National Air and Space Museum in Washington, D.C., but despite NASA's protests, a U.S. district judge has ruled that it can be owned by a private citizen.

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The decision came after a legal battle between NASA and a Chicago lawyer who bought the bag of dust in 2015 for only $995, the Chicago Tribune reported.

According to the paper, the lunar bag was mistakenly sold to Nancy Lee Carlson after a mix-up handed it to U.S. Justice Department for an unrelated investigation, which, in turn, auctioned it for the lower price. Carlson, a space enthusiast and collector, sent the bag to NASA for testing.

When results revealed traces of moon dust on the fabric, the history of the bag was uncovered, and the space agency refused to hand it back to its owner.

"This artifact was never meant to be owned by an individual," NASA said in a statement at the time. "We believe [it] belongs to the American people and should be on display for the public, which is where it was before all of these unfortunate events occurred."

But Carlson won the court battle against the agency, which was forced to return it to her in February 2017 to be auctioned off again.

The auction took place at Sotheby's in New York, where it had been expected to sell for $2 million to $4 million.

Sotheby's wrote in the listing that Carlson plans to donate some of the proceeds to charities and to set up a scholarship at Northern Michigan University.