A £1.4 million expedition is hoping to finally reveal what happened to aviator Amelia Earhart when she went missing over the South Pacific 75 years ago.

A group of scientists, historians and salvagers think they have a good idea and began a trek from Honolulu today to a remote island in the Pacific nation of Kiribati in hopes of finding wreckage of Ms Earhart's Lockheed Electra plane in nearby waters.

Their working theory is that Ms Earhart and her navigator Fred Noonan landed on a reef near the Kiribati atoll of Nikumaroro, then survived for a short time.

"Everything has pointed to the airplane having gone over the edge of that reef in a particular spot and the wreckage ought to be right down there," said Ric Gillespie, the founder and executive director of The International Group for Historic Aircraft Recovery, the group leading the search.

"We're going to search where it - in quotes - should be. And maybe it's there, maybe it's not. And there's no way to know unless you go and look."

Previous visits to the island have recovered artefacts that could have belonged to American Ms Earhart and Mr Noonan and experts say an October 1937 photo of the shoreline of the island could include a blurry image of the strut and wheel of a Lockheed Electra landing gear.

"That was the icing on the cake," said Mr Gillespie, who said the picture added to 24 years of evidence gathering used to form the group's working theory.

The photo was enough for the US State Department to hold an event to give encouragement to the privately funded expedition and enough for the Kiribati government to sign a contract with the group to work together if anything is found, Mr Gillespie said.

But the hunt using nearly 30,000lbs of specialised underwater equipment is just a sophisticated way to try to prove a hunch that could be wrong, or not provable if the plane simply floated too far or broke up into tiny, undetectable pieces.

A separate group working under a different theory plans its third voyage later this year near Howland Island.

Ms Earhart and mr Noonan were flying from New Guinea to Howland Island when they went missing on July 2, 1937, during Ms Earhart's bid to become the first woman to circumnavigate the globe.

Mr Gillespie's group raised enough funds to embark on the nearly month-long voyage through individual and corporate donors, including funds from Discovery, which plans to document the trip and show it on cable TV in August, and £160,000 worth of free shipping from FedEx of the underwater science gear.

But the trip is still nearly half a million dollars short, said Patricia Webb, a retired US Air Force colonel who helped raise funds for the trip.

If the voyage succeeds, it could add to Ms Earhart's legacy and solve a mystery that's captured widespread attention since her disappearance.

"If they find something, that adds a lot of credibility to her, to her navigator Fred Noonan, and to their survival skills because of the things that have been found so far on Nikumaroro," Ms Webb said.

The trip is planned to last about 26 days, including 10 days of searching and 16 days travelling between Honolulu and the atoll. The voyagers are using a ship owned by the University of Hawaii, an oceanographic research vessel named Kaimikai-O-Kanaloa, which translates into English as "The Searcher of the Seas of the God Kanaloa".

Mr Gillespie says the group has as good of a chance as it can expect given its equipment, including an unmanned vehicle that looks like a torpedo used for mapping terrain on the ocean floor and a tethered remote-operated vehicle that will be used to take pictures and look at objects identified in the water.

And Ms Earhart's standing as an American icon - especially to young women - and fascination in her story means it is important to solve the mystery, he said.

"That kind of inspiration matters," Mr Gillespie said. "We want to know what happened to her."

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