AFP-675 (Air Force Program-675) was a Space Shuttle experiment package that was carried into orbit on Discovery as part of STS-39.

AFP-675 consisted of six experiment packages mounted on a pallet in the Discovery's cargo bay. The total weight of the package was 5,080 kilograms (11,200 lb). The objectives of the project were:

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). The primary instruments in this experiment were a Michelson spatial interferometer and a spatial radiometer. Infrared radiation was collected through a cryogenically cooled telescope that was controlled from the flight deck. The principal investigator (PI) for the instrument was Dr. Robert R. O'Neil of the Phillips Laboratory.

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. The instrument consisted of two imaging cameras and a low-light-level TV camera mounted on the same base. Like CIRRIS, they were controlled from the flight deck. Dr. George R. Carruthers, then working for the United States Naval Research Laboratory, was the PI for this experiment.