Vanguard 1 is a U.S. satellite that became the fourth artificial Earth-orbiting satellite when it was launched on March 17, 1958, after Sputnik 1, Sputnik 2, and Explorer 1. As the first solar-powered satellite, Vanguard 1 was intended to test the launch capabilities of a three-stage launch vehicle as part of Project Vanguard, as well as to study the effects of the space environment on a satellite and its systems in Earth orbit.
 |
| Vanguard 1 "Goldcraft" launch cover, postmarked at Patrick Air Force Base on March 17, 1958. |
 |
| Vanguard 1 launch cover from "H.Flick", postmarked at Patrick Air Force Base on March 17, 1958. |
 |
| Vanguard 1 "Sarzin" launch cover, postmarked at Port Canaveral on March 17, 1958. |
(Reference from
Vanguard 1)
