WORF was delivered on April 5, 2010 by STS-131 .

The Window Observational Research Facility (WORF) is an experiment rack facility was manufactured in Huntsville, AL, by Boeing., which remotely operated payloads and crew members can perform Earth and space science research, including handheld photography, at the U.S. Laboratory Science Window on the International Space Station. WORF is based on an International Standard Payload Rack (ISPR) and utilizes avionics and hardware adapted from the EXPRESS Rack program. The rack provides a payload volume equivalent to 0.8 m3 (28 cu ft) and will be able to support up to three payloads simultaneously, depending on available resources and space available at the window. The WORF will also provide access and equipment for crew Earth observations, such as crew restraints, camera/camcorder brackets, and condensation prevention. WORF payloads include those focusing on geology, agriculture, ranching, environmental and coastal changes, and education.

Approximately 4 1/2” Diameter