[1] The second stage was a 5.8 m (19 ft) high, 0.8 m (2 ft 7 in) of diameter Aerojet General AJ-10 liquid engine burning Unsymmetrical dimethylhydrazine (UDMH) and White Inhibited Fuming Nitric Acid (WIFNA) with a helium pressurant tank.

Below the package at the bottom of the sphere was the separation device, a spring loaded tube with a timer designed to push the satellite away from the third stage after orbit was reached.

Four 76.2 cm (30.0 in) spring-loaded metal rods were folded along the equator of the sphere and would protrude radially outward when deployed, acting as a turnstile antenna.

Mounted at the end of each antenna rod was a thermistor to measure solar heating processes.

The second stage helium control bottle valve failed to open properly at engine start.

The third stage then separated and ignited, driving itself and the satellite into the Atlantic Ocean 500 km (310 mi) downrange.