Airborne radar measurements of the reentry of the Ariane 5 EPC

System Planning Corporation (SPC) fielded an airborne measurement system to observe the reentry of the Ariane 5 launch vehicle's main cryogenic stage (EPC). On March 2, 2004, the system acquired both optical images and 50-MHz radar data as the EPC reentered the atmosphere. This paper describes SPC's radar system, provides an overview of the radar data, and discusses some of the more interesting ionization-related phenomena observed as the EPC passed through the upper atmosphere.