NASA Technology Helps Smithsonian Preserve The Star-Spangled Banner

The camera, built at NASA's Goddard Space Flight Center, Greenbelt, MD, is taking images this week of the historic flag in infrared light to help preservationists identify deteriorated and soiled areas not obvious to the human eye. The camera, called the Acousto-Optic Imaging Spectrometer (AImS), was developed by Dr. David Glenar at Goddard.

Considered a national treasure, the Star-Spangled Banner flew over Fort McHenry in Baltimore, MD, during the War of 1812 and inspired the words that became the U.S. national anthem. Despite receiving extra special care at the Smithsonian's National Museum of American History (NMAH), the flag is deteriorating from decades of exposure to light, air pollution and temperature fluctuations.

"It gives me a feeling of great pride that a camera we developed to explore other planets is now exploring this historic artifact," said Dr. John Hillman, lead of the camera group at Goddard and NASA's representative on the Smithsonian team. "The flag has never been viewed this way before, and we will see what cannot be seen with the unaided eye. This exciting project is one of many practical applications for this imaging technology."

AImS will take 72 separate images that will be pieced together using a computer to create a mosaic of the massive flag, which is 30 feet wide and 34 feet long. Each image takes approximately 25 minutes to make and is composed of 200 infrared wavelengths, or colors.

Infrared light is invisible to the human eye, lying beyond the red end of the visible portion of the electromagnetic spectrum. A spectrometer in the camera will be used to separate the light and reveal its component wavelengths, similar to the way a prism separates visible light into a rainbow of colors.

"Wool is the major component in the surface composition of the flag, and contaminants found on the surface of wool reflect infrared light differently than wool itself," Hillman explained. "With AImS, we can identify where these differences are located on the flag. We are looking for things that can't be seen easily, or at all, with the human eye, such as moisture and oils. Moisture is of particular concern because, in the presence of light, it causes a chemical reaction that deteriorates wool."

"I selected AImS because of its special ability to make an image with reflected infrared light," said Suzanne Thomassen-Krauss, chief conservator of the Star Spangled Banner Project at the NMAH. "A typical infrared camera relies on thermal infrared, which is light emitted by an object due to its heat, but these cameras cannot identify contaminants on the flag because they are the same temperature as the flag itself."

After the preservation effort is complete, the Star Spangled Banner will be returned to a newly renovated Flag Hall at the NMAH in Washington, DC.

The AImS team is developing a demonstration camera for the Mars Instrument Development Program funded by NASA Headquarters. Under this program, a camera using AImS technology could be a candidate for use on robotic Mars lander missions in 2005 and beyond. The camera would be used to determine the mineral composition of Martian rocks.

The camera also can be used to explore the invisible world here on Earth. A cooperative agreement to use AImS in skin cancer research is in place with Goddard, Swales and Associates, Inc., and the Georgetown University Medical Center Department of Dermatology. "We also have had preliminary discussions with the University of Arizona, Tucson, to use our camera to analyze prehistoric sites," said Hillman.

In addition, Hillman may apply the camera in his personal efforts as a copyist at the National Gallery of Art, which involves detailed reproductions of classic art works to gain insights into the technique, motivations and intentions of the artist.

"AImS could permit a deeper understanding of a painting by revealing the underdrawing, which shows what the artist had in mind before applying the brush," Hillman said. "Another potential application for this camera is to determine the pigment used in the paint, which can distinguish an authentic piece from a forgery."

The AImS team includes Drs. Hillman and Glenar; Cheryl Vorvick and Chuck Peruso at Goddard; Dr. Nancy Chanover of the Astronomy Department at New Mexico State University in Las Cruces; Dr. Bill Blass of the University of Tennessee in Knoxville; and Dr. Jeff Goldstein of the Challenger Center for Space Science Education.