With so many pieces of evidence -- including human remains -- why does the mystery of Amelia Earhart remain unsolved?
Perhaps the biggest obstacle to discovery is the vast geographic area in which Earhart's plane might conceivably be found. No one can be certain exactly where Earhart's plane went down because of the loss of radio contact during the flight and the limiting effect of overcast skies on celestial navigation. Combing a quarter of a million square miles of ocean immediately following the disappearance yielded exactly nothing for the Navy. While subsequent efforts have focused on smaller areas, the searchable canvass remains massive, often on the order of 1,000 square miles (2,590 square kilometers).
The area's marine topography makes what's already a needle in a haystack job even more difficult: Pacific atolls rise up suddenly from the depths and are surrounded by steep shelves that lead to the ocean floor. Meanwhile, human error has also helped thwart the search for definitive proof. The human remains found on Gardner Island were lost after being examined by a doctor in the early 1940s. That rules out the definitive DNA matching technology that would likely determine conclusively whether the bones are Earhart's. (Forensic anthropologists looked at the doctor's notes in the 1990s and determined that the bones probably belonged to a woman of European descent) [source: Thurman].
These obstacles haven't deterred Earhart fans and aviation geeks from continuing their quest for answers. TIGHAR is set to launch a 30-day expedition in mid-September 2014 exploring the waters around Nikumaroro Island in an oceanographic research ship. Searchers plan to deploy two human-operated submersibles from the ship to capture detailed photo and video images of a 1-mile (1.6 kilometer) search area. At the same time, another team will comb the island's beachfront and forest in search of remnants from what might have been Earhart and Noonan's campsite [sources: Bennett-Smith, TIGHAR].
Searchers have continued to find significant clues. In 2013, TIGHAR announced that it had used sonar imaging to uncover evidence of a 22-foot (7-meter) object that may be a piece of Earhart's aircraft. Resting 600 feet (183 meters) below the surface of the Pacific Ocean and west of Nikumaroro, the image resembles the fuselage of Earhart's Lockheed Electra [source: Bennett-Smith].
There's good reason to believe that all or most of the plane remains intact. An hour before their last transmission, Earhart told the Coast Guard she and Noonan were flying at a low altitude, around 1,000 feet (304 meters). At around 100 miles per hour (161 kph), the Lockheed Electra could conceivably have maintained its integrity. If it did, the plane may still be in perfect shape, preserved in the oxygen-deprived depths of the South Pacific. Perhaps sooner rather than later we'll get to the bottom of the mystery surrounding Earhart's disappearance.