The Explorer 23 or S 55c micrometeoroid satellite was the third in the series of S 55 micrometeoroid satellites orbited by NASA. November 6, 1964 at 12:02 UTC · Launch Successful Scout X-4 — National Aeronautics and Space Administration, to Low Earth Orbit Launch Area 3, Wallops Flight Facility, Virginia, USA The world's 379th orbital launch attempt, and 86th of 1964. Data: Launch Library 2, The Space Devs. Image by U.S. Air Force (Department of Defense Image Use Policy) via The Space Devs.