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An extremely rare document signed by Amelia Earhart that provides details of her doomed aircraft has surfaced after half a century hidden in an attic.

The aviation pioneer filled out the document to enter the 1936 National Air Races with her famous but ill-fated Lockheed Electra. Less than a year after competing in the races, Earhart disappeared while attempting to fly the Lockheed plane around the world.

Earhart and navigator Fred Noonan went missing on July 2, 1937, during a flight from Papua New Guinea to Howland Island in the Pacific. Their fate became one of the great mysteries of the 20th century and is still hotly debated.

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The document is part of an archive of 64 forms filled out by aviators of the era that will be unveiled by a historical document dealer, the Raab Collection, on Thursday. This was Earhart’s first and last national race in the Lockheed before she attempted her circumnavigation of the globe.

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The archive of documents (The Raab Collection)

The Earhart document and the accompanying archive are valued at $75,000.

The 1936 National Air Races represented a breakthrough event for female aviators, with women broadly eligible to compete against men for the first time, according to the Raab Collection. In addition to Earhart, Jacqueline Cochran, Louise Thaden, Laura Ingalls, Grace Prescott and Helen MacCloskey took part, with Thaden winning the prestigious Bendix trophy.

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The Earhart document, in particular, offers a fascinating glimpse into the life of an aviation icon. “It was discovered in a box in the back of an attic,” Nathan Raab, one of the owners of the Raab Collection, told Fox News. The collection's research indicates that no other such document has ever reached the market, he added.

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Earhart lists details of her ill-fated Lockheed plane in the signed document (The Raab collection)

In the document, Earhart lists technical details of her plane, its registration number and its date of manufacture – July 20, 1936. “To see Earhart describe her "new" plane in such detail is remarkable,” Raab told For News.

The archive's original owner gave it as a gift to a colleague more than 50 years ago, according to the Raab Collection. The colleague rediscovered the box earlier this year.

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Earlier this year, a scientific study claimed to shed new light on the decades-long mystery of what happened to Earhart.

Richard Jantz, an emeritus anthropology professor at the University of Tennessee, argued that bones discovered on the Pacific island of Nikumaroro in 1940 were likely Earhart’s remains. The research contradicts a forensic analysis of the remains in 1941 that described the bones as belonging to a male. The bones, which were subsequently lost, continue to be a source of debate.

The first woman to fly solo across the Atlantic Ocean, Earhart was one of the most famous people in the world at the time of her disappearance. A number of theories have emerged about her fate.

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One well-publicized theory is that Earhart died a castaway after landing her plane on the remote island of Nikumaroro, a coral atoll 1,200 miles from the Marshall Islands. Some 13 human bones were found on Nikumaroro, also known as Gardner Island, three years after Earhart’s disappearance.

Amelia Earhart-Last Flight

In this May 20, 1937 photo, provided by The Paragon Agency,shows aviator Amelia Earhart and her Electra plane, taken by Albert Bresnik at Burbank Airport in Burbank, Calif. It was a clear spring day in 1937 when Amelia Earhart, ready to make history by flying around the world, brought her personal photographer to a small Southern California airport to document the journey's beginning. (Albert Bresnik/The Paragon Agency via AP)

While some people are convinced that Nikumaroro is Earhart’s final resting place, another theory suggests that she met her end on Mili Atoll in the Marshall Islands.

Last year, controversy swirled around a photo that was touted as providing a vital clue as to Earhart’s fate.

The Associated Press contributed to this article.

Follow James Rogers on Twitter @jamesjrogers