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The fragment remains on the ocean floor just off the Florida coast near Cape Canaveral as NASA determines the next step. It remains the property of the U.S. government. The families of all seven Challenger crew members have been notified.
"We want to make sure whatever we do, we do the right thing for the legacy of the crew," Ciannilli said.
Roughly 118 tons (107 metric tons) of Challenger debris have been recovered since the accident. That represents about 47% of the entire vehicle, including parts of the two solid-fuel boosters and external fuel tank.
Most of the recovered wreckage remains buried in abandoned missile silos at Cape Canaveral Space Force Station. The exception is a left-side shuttle panel on display at Kennedy Space Center's visitor complex, alongside the charred cockpit window frame from shuttle Columbia, which broke apart over Texas during re-entry in 2003, killing seven astronauts.
Far less has been recovered of Columbia - 42 tons (38 metric tons) representing 38% of the shuttle. The Columbia remains are stored in converted offices inside Kennedy's massive hangar.
Launched on an exceptionally cold morning, Challenger was brought down by eroded O-ring seals in the right booster. Columbia ended up with a slashed left wing, the result of foam insulation breaking off the external fuel tank at liftoff. Mismanagement was also blamed..
A History Channel documentary detailing the latest Challenger discovery airs Nov. 22.