Amelia Earhart's attempt to become the first woman to fly around the globe at the equator ended in mystery when she and her navigator, Fred Noonan, disappeared over the Pacific Ocean in July 1937.
With the 90th anniversary of her disappearance on the horizon, a new expedition is setting out to finally determine what happened over the vast Pacific. This expedition has what it believes is crucial new evidence.
The team from Purdue University in Indiana and the Archaeological Legacy Institute (ALI) is scheduled to depart for the uninhabited island of Nikumaroro on Saturday to determine if an anomaly in the island's lagoon is Earhart's missing plane.
Part of the low-lying Pacific island nation of Kiribati, Nikumaroro has long been considered the place where Earhart and Noonan died.
The pair took off from New Guinea on July 2, 1937, on the leg to the island of Howland, where they were to refuel before continuing on to Hawaii and completing the circumnavigation in California.
Something went amiss en route, however, and even though a US Coast Guard ship could hear Earhart's radio transmissions and her Lockheed Electra must have been tantalizingly close, she was never found.
One of the last messages said she was running on a north-south navigational line that gave her the best chance of finding land before her fuel ran out. That line went through Nikumaroro.
Landing on a coral reef
In 1988, researchers from the International Group for Historic Aircraft Recovery (TIGHAR) were the first to suggest that Earhart could have reached Nikumaroro and landed on its fringing coral reef.
TIGHAR's first visit to the island was in 1989, and the group has returned seven more times, turning up compelling artifacts, including lengths of aircraft aluminum and plexiglass from a windscreen.
The group found a scent bottle, a zip made in Pennsylvania in the mid-1930s, parts of a pocket knife of the same brand listed in the aircraft inventory, and the heel of a woman's shoe.
Archive research discovered that human remains discovered on the island in 1940 were initially believed to be of Earhart or Noonan — but were lost in the chaos of the Pacific war.
Despite the searches, no one has yet found the "smoking gun" artifact, an item that could only have come from the doomed flight.
Satellite images offer fresh hope
Expedition leader Rick Pettigrew, executive director of the Archaeological Legacy Institute (ALI), believes the elements may have uncovered incontrovertible evidence.
A powerful tropical cyclone tore through the central Pacific in 2015, shifting geographical features on the island and in its lagoon. Satellite images taken over the following years showed what might be the outline of an aircraft fuselage and wings in shallow water off the Taraia promontory.
"This object in the satellite images is exactly the right size to represent the fuselage and tail of the Electra," the ALI website states. "It also appears to be very reflective and is likely to be metallic. It lies in very shallow water, largely covered by sediment, in a place where the current would bring an object floating into the lagoon through Tatiman Passage, the opening to the ocean and the reef."
Pettigrew's 17-strong team intends to focus all its efforts on the place where the images indicate debris may be located, using drone photography, remote sensing with magnetometers and sonar units. If the initial results are positive, a hydraulic dredge will excavate sediment.
"Once we have a sufficient portion of the object exposed, we should be able to identify it," according to the ALI's expedition plan. "If it is made of aircraft aluminum and has the specific shape and rivet patterns of the Electra, we will know that we have found the remains of Earhart's aircraft."
In search of a 'smoking gun'
Much of the ALI's theory is based on the research and fieldwork carried out by TIGHAR, but its executive director, Ric Gillespie, is not convinced the researchers will find the "smoking gun."
"The object visible in old satellite imagery that Pettigrew believes is aircraft wreckage does not look like aircraft wreckage," Gillespie told DW. "It looks like a dead pandanus tree that was uprooted in a storm and washed up on Taraia."
"Pettigrew thinks the wreckage is no longer visible because it is buried in silt," Gillespie noted. "He has never been to that location and does not understand that the silt there is only a few inches deep."
Teams from TIGHAR searched the same location in 2001 and 2007 with metal detectors and drew blanks, he said. Yet Gillespie remains convinced that Earhart was on Nikumaroro.
"I think the aircraft sank immediately after being washed over the reef edge and was smashed to pieces in the surf," he said. "Major components were eventually buried in underwater landslides … or grown over with coral. We have found what there is to find."
Dorothy Cochrane, who has monitored progress in the search for Earhart for more than 35 years as curator at the Smithsonian National Air and Space Museum in Washington, DC, and continues to do so since her recent retirement, says Earhart still holds fascination for so many people "because it is 'the greatest unsolved mystery of the 20th and continuing into the 21st centuries.'"
An alternative scenario
She has a different view of what happened in 1937. She argues that if Earhart was nearly out of fuel while still close to Howland, it would have been impossible to fly another 640 kilometers (400 miles) to Nikumaroro. Cochrane also says that items cited as evidence of a castaway on the island can be explained by other visitors and by a small settlement that existed there for several years.
"I believe that Earhart and Noonan were in the general vicinity of Howland Island, based on the facts of the flight, but just could not find it before they ran out of fuel," she said.
"Howland Island was a tiny speck in the morning light of a vast sea," she said, suggesting Earhart could not establish radio contact to guide her the last few miles to her destination.
Cochrane believes the Electra lies on the seabed near Howland. Others have advanced this theory, and several searches of the area have been carried out in recent years.
If Pettigrew's lead pays off, however, it will conclude aviation's nearly 90-year puzzle.
