THE 80-YEAR MYSTERY OF AMELIA EARHART UNRAVELS

It may may one of the enduring mysteries of our time: What happened to Amelia Earhart?

Tonight we’ll know more, thanks to a new two-hour History Channel special.

But it seems there still isn’t a happy ending to the story of the legendary American aviation pioneer — the first woman aviator to fly solo across the Atlantic Ocean.

Earhart received the U.S. Distinguished Flying Cross for braving and conquering the nonstop trans-Atlantic flight on May 20, 1932. But five years later she and navigator Fred Noonan were flying the final leg of a round-the-world flight when they and their plane disappeared on July 2, 1937.

Earhart was but three weeks shy of turning 40, and she’d already pushed many earthbound limits.

She’d written best-selling books about her flying experiences and helped form The Ninety-Nines, an organization for female pilots. In 1935, Earhart became a visiting faculty member at Purdue University as an adviser to aeronautical engineering and a career counselor to female students. She was a member of the National Woman’s Party and an early supporter of the Equal Rights Amendment. She also was a pioneer of what today is called open marriage, having written to her husband, George P. Putnam, on their wedding day: “I want you to understand I shall not hold you to any midaevil [sic] code of faithfulness to me nor shall I consider myself bound to you similarly.” She pointedly kept her own name. Now her story has a new chapter.

On Wednesday, researchers revealed that part of tonight’s History Channel special, “Amelia Earhart: The Lost Evidence,” will show and discuss a newly discovered photograph that lends credence to one of the theories of her disappearance: that Earhart and Noonan survived their plane’s crash 80 years ago in the Marshall Islands, only to be taken prisoner by the Japanese, who then controlled much of the region.

Another long-standing theory had been that the plane ran out of gas and crashed in the ocean, then sank. Still another was that Earhart died a castaway on a remote island.

A third theory — one that seems to gain legs with this report — was that she was on a covert spy mission for the Roosevelt administration and was taking photographs in the Pacific to see whether the Japanese were fortifying the Marshall Islands. Some even hypothesized that she was shot down by the Japanese and either beheaded or died in prison.

The photo, found in a long-forgotten, formerly top-secret file in the National Archives, shows a woman who resembles Earhart and a man who strongly resembles Noonan, on a dock. The photo also shows a Japanese ship, Koshu, towing a barge with something that appears to be about 38-feet-long — the same length as Earhart’s plane.

Independent analysts told History the photo appears legitimate and undoctored. Shawn Henry, former executive assistant director for the FBI and an NBC News analyst, has studied the photo and feels confident it shows the famed pilot and her navigator.

The investigative team behind the special believes the photo, marked Jaluit Atoll in the Marshall Islands, may have been taken by someone who was spying for the U.S. on Japanese military activity in the Pacific. The team also believes Earhart and Noonan died as Japanese prisoners. Japanese authorities told NBC News they have no record of Earhart being in their custody, but no Japanese officials from Earhart’s time are alive today, and many Japanese military documents were destroyed during the war.

For decades, locals on the atoll claimed they saw Earhart’s plane crash before she and Noonan were taken away. They said the military told them the woman in the plane was a spy and not to talk about it. Native school kids insisted they saw Earhart in captivity. The story was even documented in postage stamps issued in the 1980s.

Gary Tarpinian, the executive producer of the History special, said his researchers believe that the Koshu took her to Saipan in the Mariana Islands, and that she died in custody there. How and when remain a mystery.

Another mystery is whether the U.S. government knew who was in the photo. If it was taken by a spy, the U.S. may not have wanted to compromise that person by revealing the image, but researchers say the spy was later executed by the Japanese.

NBC News’ Tom Costello noted Wednesday on the “Today” show that the photo was part of a file compiled by the Office of Naval Intelligence gathering information about Japanese movement in the area. Costello noted: “Another file, Office of Naval Investigations, a thick file on Amelia Earhart and the Marshall Islands, 170 pages, is missing. Was it purged? If so, when and by whom?”

One possible explanation is diplomacy — and age-old American political spin.

After the war, the U.S. was trying to build up a new ally — Japan, which we had just conquered.

“If it became well known that in fact Japan had put to death America’s sweetheart, that would not have gone over very well with the American public,” Costello hypothesized.

Here’s a surer bet. If it happened today — in this age of the internet, Facebook and Twitter — the mystery wouldn’t take 80 years to untangle.