The aluminum panel was found on a small pacific island close to where Amelia Earhart and her navigator, Fred Noonan, last made radio contact. Overlaid on the panel are the neutron radiography results, revealing information not visible to the naked eye. Credit: Kenan Ünlü/Penn State University.
In 1991, Ric Gillespie, who leads The International Group for Historic Aircraft Recovery (TIGHAR), discovered a metal panel on a Pacific island close to where Amelia Earhart and her navigator last made radio contact. Perhaps it came from Earhart’s plane or perhaps not, but either way, a technology did not exist at the time that could peer past decades of damage from rolling around the ocean floor.
While watching a documentary on Earhart and the metal panel in 2020, Daniel Beck, engineering program manager in Penn State’s Radiation Science & Engineering Center (RSEC), realized the technology did exist now—the Penn State Breazeale Reactor.
Beck proposed using neutron radiography and neutron activation analysis to examine the external and internal makeup of the panel, respectively. Neutron radiography involves using neutron beams from the Breazeale Nuclear Reactor. A sample is set in front of the neutron beam, and a digital imaging plate is placed behind the sample. The neutron beam passes through the sample into the imaging plate, and an image is recorded and digitally scanned. Meanwhile, neutron activation analysis helps precisely identify the make-up of materials at parts-per-million or parts-per-billion level sensitivity.
The technology slowly but surely revealed hidden elements, but the team hoped for more.
“The first images were really exciting, but we knew we needed to do better to confirm what we thought we saw,” said Beck. “We were already in the process of upgrading the neutron imaging facility, so the panel provided the perfect sample to optimize our neutron radiography capabilities.”
After upgrading the neutron imaging facility and refining their techniques over the last year, Beck and team recently completed a final analysis of the panel—and observed something new.
They found what looks like stamped or painted marks of letters and numbers on the panel that could be from the original manufacturer. The characters clearly read XRO, D24 and 3D, and then either 335 or 385.
“We don’t know what they mean, but they are the first new information from this panel that has been examined by various experts with different scientific techniques for over 30 years,” said Kenan Ünlü, director of RSEC and professor of nuclear engineering.
Gillespie is now consulting with forensic analysts to decipher the characters and what they might represent. If researchers can conclusively determine what the marks mean, such as a production number, it could confirm the panel came from Earhart’s plane—or could definitively rule out the possibility.
And while that’s not the end of the story for the panel, the Penn State Breazeale Reactor has recently taken on a more contemporary challenge—distribution of microplastics in environment. Despite their prevalence, not enough is understood about how microplastics disperse and their effects.
Led by Alibek Kenges, a doctoral student in nuclear engineering, researchers at the RSEC recently had much success examining handfuls of sand for microplastics.
“The neutron imaging technique worked perfectly: the resulting image doesn’t show the sand at all, but the microplastics, from a millimeter to a few millimeters in size, lit up like Christmas lights,” said Kenges.
Kenges is now examining different types of filtration materials used to sieve microplastics from water samples. He found that the neutron imaging approach could potentially be used to detect microplastics in the water filters, but the technique needs refinement to account for uncertainties related to parts of the imaging system.
Now, the team is performing controlled experiments to establish the detection limits of the system and further finetune the methodology. Ultimately, Kenges and team hope the visualization of microplastics in samples like sand, water and soil will help better inform environmental approaches to this global pollution problem.
The irony of the trajectory of the Breazeale Reactor at RSEC is not lost on anyone.
“We started by revealing a potential clue for a mystery almost a century old, which pushed us to optimize the imaging facility at RSEC. Now, we’re learning new information about something that will impact generations to come,” said Beck.