Much of the 186 years of wear and tear on the Star-Spangled Banner is obvious to the naked eye. It's worn out. Gauging the wear on individual fibers in the flag is harder. That's where the NASA instrument helped. The camera acted as a high-tech magnifying glass, pinpointing moisture damage in the flag's wool.
Moisture causes chemical reactions that disintegrate the wool fibers.
Because water absorbs near-infrared light much more readily than visible light, the spots appear as dark blotches to the infrared camera. To the naked eye, the same spot might look perfectly fine. Oil stains are similarly easier to see in the near-infrared. Conservators hope to complete analysis of the images by this spring, producing a detailed map of where they should concentrate their conservation efforts. Infrared cameras could have other earthly applications as well, including the detection of skin cancer, photographing of prehistoric sites and spotting ice on airplane wings.