WEST LAFAYETTE, Oct. 15 -- A 17-person team that spent five days at sea to reach a Pacific lagoon says it will know within days whether a shape visible in photographs since 1938 is Amelia Earhart's lost Lockheed Electra. Its confidence is also its risk: the last time anyone thought a sonar image showed her plane, it turned out to be a rock.

The underwater survey of the lagoon off Nikumaroro, an island in Kiribati, began Wednesday, with stormy weather slowing the first day, according to the team's account to CBS News. Purdue University and the Oregon-based Archaeological Legacy Institute are running the expedition, led by Purdue's Steve Schultz and the institute's Richard Pettigrew.

The target is what they call the Taraia Object, a visua...