America's First Successful Satellite
Explorer I was America's first space success. Four additional Explorers were
launched in 1958, but only two achieved orbit.
The final Explorer (Explorer VI) was renamed Explorer-Beacon. The slightly
elongated spacecraft was modified to carry a tightly packed, highly reflective
silver mylar balloon. Once in orbit, the upper section of the satellite would
be jettisoned and the 12-foot-diameter balloon would inflate. Scientific
experiments to bounce radio and light signals off the inflated balloon from
ground stations were planned. However, the satellite failed to reach orbit
during its only launch attempt in October 1958.
The Explorer on display above was an actual backup unit to the original
satellite. It was modified for the Beacon program (notice the silver balloon
still folded up in the satellite), but the program was cancelled before this
modified unit could be launched.