Vanguard SLV-1, also called Vanguard Satellite Launch Vehicle 1 was hoped to be the second successful flight of the American Vanguard rocket following the successful launch of the Vanguard 1 satellite on rocket Vanguard TV-4 in March 1958. Vanguard SLV-1 launched on May 27, 1958 03:46 GMT. It was launched from Launch Complex 18A at the Cape Canaveral Air Force Station. At second stage separation, there was a momentary pitching motion registered by the rate gyros which resulted in an incorrect attitude reference. The second stage placed the third stage on a trajectory approximately 63° up from the intended flight path. It arced upward and reached a peak altitude of 2200 miles before reentering and breaking up over South Africa. The pitching motion was deemed to be a rupture in the second stage engine thrust chamber due to high frequency combustion instability at engine shutdown. On subsequent flights, the second stage was modified to prevent the possibility of an oxidizer-rich shutdown.
Vanguard SLV-1 carried the Vanguard 2B satellite, equipped with Lyman Alpha ultraviolet detectors and a magnetosphere measurement device. The satellite payload weighed 10 kg (22 lb). The rocket reached an apogee (the highest point of the rocket's flight) of 3,500 km (2,200 mi).
- Mallove, Eugene F. and Matloff, Gregory L. The Starflight Handbook: A Pioneer's Guide to Interstellar Travel, Wiley. ISBN 0-471-61912-4.