Few aviation mysteries have captivated the public as much as the disappearance of Amelia Earhart, whose plane vanished over the Pacific Ocean in 1937 as she was attempting to become the first female pilot to fly around the world.

In the decades since, conspiracy theories about what really happened to Earhart and her navigator, Fred Noonan, have abounded. Some speculate that their Lockheed Model 10 Electra crashed and sank to the bottom of the Pacific. Others claimed the Japanese captured the pair, thinking they were spies.

Last year, a Pennsylvania-based group called International Group for Historic Aircraft Recovery (TIGHAR) repositioned the spotlight on an alternate theory: With their fuel rapidly depleting, Earhart and Noonan used celestial navigation to land on a small coral atoll about 400 miles south of Howland Island, their original destination.

Injured but still alive after a crash-landing on what was then called Gardner Island, Earhart and Noonan attempted to call for help for almost a week using the radio from their wrecked plane, TIGHAR posited.

Now the group is launching an ambitious expedition to try to prove its theory. On Saturday, TIGHAR researchers plan to sail to Gardner Island, now called Nikumaroro, with a pack of forensically trained border collies, according to National Geographic, which is co-sponsoring the trip and first reported the news.

The mission: For the dogs to sniff out human bones that, through DNA matching, would confirm Earhart and Noonan landed and then perished on that island.

Any such “smoking gun” would require an extraordinary convergence of circumstances, TIGHAR director Ric Gillespie told The Washington Post.

This summer marks 80 years since Earhart and Noonan disappeared; even if they did in fact die on Nikumaroro, there's a good chance that the island's large population of Polynesian rats chewed up many of the bones in the decades since, Gillespie said.

“DNA likes cold and dark, and there's just not a lot of cold and dark on Nikumaroro,” Gillespie said. “And again, it's been 80 years. Even if you have a bone, that there's going to be surviving, sequenceable DNA in that bone — it's pretty remote.”

There is, however, the possibility that the island's coconut crabs — giant arthropods known to be able to climb trees — would have scavenged some skeletal remains in their burrows.

And that possibility is keeping the expedition's crew hopeful.

“The crabs are our friends,” Fred Hiebert, archaeologist in residence at the National Geographic Society, told the magazine. “If the dogs don’t find anything, we’ll have to think about what that means. … But if the dogs are successful, it will be the discovery of a lifetime.”

The border collies — named Berkeley, Kayle, Marcy and Piper — are from the Institute for Canine Forensics and have trained for years together sniffing out historic and prehistoric burial sites, Adela Morris, the group's founder, told The Washington Post.

This will be the first time the dogs have ridden on a ship for an extended period of time. The border collies also must withstand Nikumaroro's heat, which can make it difficult for them to capture scents, and the island's sharp coral terrain, she said.

“You know, stranger things have happened,” Morris said. “The conditions are extremely difficult. … But if you don't try a technique, you'll never know.”

In a video presentation posted last summer, Gillespie insisted that TIGHAR's alternate theory was, in fact, “the oldest theory” and one heavily supported by historical documents, photographs and identifiable artifacts.

“Earhart made a relatively safe landing at Gardner Island and sent radio distress calls for six days,” Gillespie declares as his hypothesis in the video. Forty-seven of those messages, heard by professional radio operators between July 2 and 7 of 1937, appear to be credible, he said.

Among those radio operators was a then-16-year-old Florida girl named Betty Klenck, who jotted down nearly two hours of what she heard over her shortwave radio in a notebook, which TIGHAR later analyzed.

“What she heard is not just a woman calling for help. She heard background conversation. There was a man with her who seemed to be out of his head,” Gillespie says in the video, linking the man in the background to Noonan. “And he was grabbing the mic and saying things. The whole thing reads like a modern 911 call.”

Bolstering his hypothesis, Gillespie said, was the fact that British officials in 1940 discovered bones on Nikumaroro that he thinks probably belonged to Earhart.

British officials discovered a partial human skeleton in 1940 and wondered whether it might belong to the famed aviator. So officials shipped the 13 bones to a medical school in Fiji, where they were examined by D.W. Hoodless, a physician.
Hoodless took measurements and concluded that the bones were probably those of a short, stocky European man — not Earhart's.
The bones were then discarded.
But TIGHAR investigators think Hoodless was wrong.
In 1998, the group took the measurements from Hoodless and ran them through a more robust anthropological database. The bones, they determined, could have belonged to a taller-than-average woman of European descent.
Earhart was 5-feet-7, or, by some accounts, 5-feet-8 — several inches taller than average.

This week's trip to Nikumaroro will be TIGHAR's 12th expedition to the island since the late 1980s, when Gillespie first started exploring theories about Earhart's disappearance in earnest.

His research — some might say obsession — has put him at odds with other Earhart enthusiasts, especially those in what he calls the “crashed-and-sank” camp.

But Gillespie said he is optimistic that his findings over the decades have been scientifically sound.

“We have a tremendous body of evidence, all pointing to the same conclusion,” he told The Post. “We're still up against this thing where you've got to have DNA or a part of the airplane where it originally was. And that's a really tall order. But that's why we're back out there.”

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