Apollo 16 Mission
Science Experiments - Far Ultraviolet Camera/Spectrograph
The Far Ultraviolet Camera/Spectrograph took pictures and spectra of astronomical objects in ultraviolet light.
Ultraviolet (UV) light is a type of electromagnetic radiation at wavelengths that are shorter than can be seen with the human eye. Most UV light from astronomical sources is absorbed by the Earth's atmosphere and does not penetrate to the surface. Nevertheless, studying the UV emission of astronomical objects is important because such emissions come from objects that are much hotter than our Sun.
The Far Ultraviolet Camera/Spectrograph was carried on Apollo 16. It used a 3-inch telescope to obtain images and spectra at wavelengths between 500 and 1600 Angstroms; (visible light corresponds to wavelengths of 4000-7000 Angstroms). Emission at these wavelengths comes primarily from very hot stars of spectral classes O, B, and A, with surface temperatures of 10,000° to 50,000° K. For comparison, the temperature at the visible surface of the Sun is about 5800° K or 11,000°F. Stars as faint as magnitude 11, or 100 times fainter than can be seen with the human eye, were recorded. Results were recorded on a film cartridge and returned to Earth for analysis. A total of 178 frames of film were obtained. The telescope was periodically reoriented by the astronauts in order to study various parts of the sky. Among the objects studied were the Earth's upper atmosphere and aurora, various nebulae and star clusters, and the Large Magellanic Cloud, which is a satellite galaxy of the Milky Way galaxy. A back-up version of this experiment was later flown on the final Skylab flight and was used to study ultraviolet emission from Comet Kohoutek and other objects.