It's a mystery that's puzzled the world for more than 80 years: what happened to Amelia Earhart?
The famous aviator and her navigator, Fred Noonan, were on the second-to-last leg of their trip around the world when they disappeared on July 2, 1937, in the South Pacific.
Now, legendary explorer Bob Ballard, who found the sunken wreckage of the Titanic in 1985, is launching an expedition to find Earhart's plane and documenting the quest in a two-hour National Geographic documentary.
Ballard, National Geographic explorer-at-large, and his team plan to search deep underwater for clues.
Earhart was hoping to become the first woman to circle the globe, and she and Noonan mostly followed the equator as they flew around the world.
There are many theories about what could have happened to Earhart and Noonan, including that their plane crashed somewhere over the ocean or that they were captured and taken prisoner by the Japanese.
In 2017, that theory got a boost from a photo discovered in the National Archives that many thought showed Earhart and Noonan on a dock being taken prisoner.
The photo was explored in a History Channel documentary, "Amelia Earhart: The Lost Evidence," in which experts said the figures in the photo bore many similarities to Earhart and Noonan.
But a military history blogger named Kota Yamano found the photo in a Japanese-language travel book that was published in 1935, two years before Earhart disappeared, sending researchers back to the drawing board.
In 2018, remains discovered on Nikumaroro island in the South Pacific 80 years ago were forensically tested by researchers at the University of Tennessee, who concluded they likely belonged to Earhart.
"In the case of the Nikumaroro bones, the only documented person to whom they may belong is Amelia Earhart," researcher Richard L. Jantz concluded in a paper published in the journal Forensic Anthropology.
Earhart's plane has never been recovered, but Ballard and the National Geographic team hope that finding evidence of it could help solve the Earhart mystery once and for all.