 3", the WB-57F was used as a flying testbed for the evaluation of multispectral sensors in a "near-space" environment to collect data to be correlated with similar data collected at low altitude and on the ground.The Air Force contracted with NASA to provide the aircraft on the condition that its sensor package be easily removed to reconfigure the aircraft quickly for its national security mission if necessary.The "Rivet Rap" was therefore modified to carry aerodynamically faired, plug-in pallets developed by General Dynamics to house both NASA and Air Force primary mission equipment.