AFP-675 (Air Force Program-675) was a Space Shuttle experiment package that was carried into orbit on Discovery as part of STS-39.
The objectives of the project were:[1] The Cryogenic Infrared Radiance Instrumentation for Shuttle (CIRRIS 1A) experiment was designed to measure the spectral, spatial, and temporal properties of the Earth's limb (edge).
[2] The Far Ultraviolet Cameras experiment was to capture imagery and photometry of naturally occurring and man-made emission phenomena such as airglow and diffuse aurora.
Secondary missions were to study interplanetary and interstellar objects (such as comets and stars) and to make atmospheric density measurements by stellar occultations.
Dr. George R. Carruthers, then working for the United States Naval Research Laboratory, was the PI for this experiment.