THE UVISI INSTRUMENT

The Ultraviolet and Visible Imagers and Spectrographic Imagers (UVISI) instrument is a complex oi nine sensor units (five spectrographic ima gers and four imagers) and multiple processors that will provide detai led images and spectra of targets for the Midcourse Space Experiment m ission. Imaging and spectroscopy each cover the range from 110 nm (far ultraviolet) to 900 nm (near infrared). UVISI is intended to investig ate a multitude of celestial, atmospheric, and point sources over its planned 4-year lifetime. At 104 W and 211 kg, it is not only the large st free-flying instrument ever built at APL, but is also larger than 4 7 of the 55 APL-built spacecraft and more complex than many of them. T his article discusses the specifications of UVISI and its hardware and software features. It also attempts to give the reader a sense of the design trade-offs made during UVISI development that resulted in its present configuration.