FIRE (Flight Investigation of Re-Entry) was a high-speed reentry heat research program to obtain data on materials, heating rates, and radio signal attenuation on spacecraft reentering the atmosphere at speeds of about 24,500 miles per hour. April 14, 1964 at 21:42 UTC · Launch Successful SM-65D Atlas — United States Air Force, to Suborbital Launch Complex 12, Cape Canaveral SFS, FL, USA Data: Launch Library 2, The Space Devs. Image by United States Air Force (Department of Defense Image Use Policy) via The Space Devs.