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Far-ultraviolet camera / spectrograph

Since the 1960s, George R. Carruthers has been a pioneer in the use of ultraviolet spectroscopy to learn more about the earth and the universe.

Born in Cincinnati in 1939, Carruthers was an inventive and inquisitive child. At age 10, his enthusiasm for books of science fact and fiction led him to construct his own telescope, from cardboard tubing and lenses he had ordered through the mail. As a result, Carruthers was already an experienced, if amateur, astronomer by the time he entered the University of Illinois (1957). There, he added the disciplines of Physics and Nuclear Engineering to his expertise. In time, he earned a B.S. (1961) and M.S. (1962) in Physics, and a Ph.D. in Aeronautical and Astronomical Engineering (1964).

After graduate school, Carruthers gladly accepted a position as Research Physicist with the Naval Research Laboratory (NRL) in Washington, DC (1964). He has worked there ever since.

Being an inventor as well as a physicist, Carruthers excelled at developing new instrumentation, often as Principal Investigator, for research projects. Carruthers became an expert in ultraviolet radiation---in fact, he later became Head of NRL's Ultraviolet Measurements Branch (1982). But his first major contribution in this field was to lead the team that invented the far ultraviolet camera / spectrograph used for the Apollo 16 mission to the moon (1972).

Ultraviolet (UV) "light" is the swath of electromagnetic radiation (wavelength from about 400 to 4 nanometers) between visible light and x-rays. UV emissions give the best clues to the nature of very hot celestial objects---for example, stars from twice to ten times as hot as our sun. But the earth's atmosphere absorbs most UV emissions from space; so a UV camera operating on the moon would open a whole new world of information.

Carruthers led the team that invented that camera: they surmounted all challenges of instrumentation and design to create a 50-pound, gold-plated apparatus that recorded radiation from the upper half of the UV spectrum. The Apollo 16 crew deployed Carruthers' camera on the moon's surface at various points of view, and returned with almost 200 UV "photos," including views of newly discovered stars and nebulae. The camera itself had to be left behind, but a second version of it was used aboard the final Skylab flight (1973) to study the comet Kohoutek.

Carruthers' far-ultraviolet spectrograph also provided new views of the Earth: specifically, of the ionosphere, the stratum of our atmosphere about 50-400 miles above the surface. Carruthers' most recent work has also focused here, including UV imaging of the Earth's polar auroras and of airglow---a faint photochemical luminescence found in the upper atmosphere.

In 1987, Carruthers was named Black Engineer of the Year; in 1997, he joined the Independent Scientific Review that advises the Hubble Space Telescope Project. Besides working at NRL and collaborating with NASA, Carruthers is actively promotes science and technology among young people, especially African Americans. After 35 years at work, George Carruthers continues to be a driving force in astrophysics research and science education.

[Sept. 1998]

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