The unique PEPP-Aeroshell (Planetary Entry Parachute Program) was a test vehicle to test the aerodynamic properties of the parachutes for the Voyager (later renamed Viking) Mars probes. It was launched by high altitude balloon from Walker Air Force Base (Roswell Air Field). Upon reching a height of x km, the vehicle was released and the solid fueled rockets (12 Falcon or 8 Sword-1 motors) accelerated the test vehicle upwards. At burn out the aeroshell was released from the dummy payload, which then unfurled the parachutes. The 15-foot disk-shaped flight units were flown only four times: August 30, 1966; July 28, 1967; August 15, 1967; and August 22, 1967.

(from http://space.skyrocket.de/doc_lau/pepp-aeroshell.htm)