 Vanguard rocket undergoing static test on launch pad | |
| Names | Vanguard Test Vehicle-Three Backup |
|---|---|
| Mission type | International Geophysical Year |
| Operator | Naval Research Laboratory |
| COSPAR ID | VAGT3B |
| Mission duration | 62 seconds (failed to orbit) |
| Spacecraft properties | |
| Spacecraft | Vanguard 1B |
| Spacecraft type | Vanguard |
| Manufacturer | Naval Research Laboratory |
| Launch mass | 1.5 kg |
| Dimensions | Sphere of 16.3 cm in diameter |
| Start of mission | |
| Launch date | 5 February 1958, 07:33 GMT |
| Rocket | Vanguard |
| Launch site | Cape Canaveral, LC-18A |
| Contractor | Glenn L. Martin Company |
| End of mission | |
| Decay date | Failed to orbit |
| Orbital parameters | |
| Reference system | Geocentric orbit (planned) |
| Regime | Low Earth orbit |
| Perigee altitude | 655 km |
| Apogee altitude | 3840 km |
| Inclination | 34.2° |
| Period | 132.0 minutes |
Vanguard TV-3BU, also called Vanguard Test Vehicle-Three Backup, was the second flight of the American Vanguard rocket. An unsuccessful attempt to place an unnamed satellite, Vanguard 1B, into orbit, the rocket was launched on 5 February 1958. It was launched from LC-18A at the Cape Canaveral Air Force Station. Fifty-seven seconds after launch, control of the vehicle was lost, and it failed to achieve orbit. At 57 seconds, the booster suddenly pitched down. The skinny second stage broke in half from aerodynamic stress, causing the Vanguard to tumble end-over-end before a range safety officer sent the destruct command. The cause of the failure was attributed to a spurious guidance signal that caused the first stage to perform unintended pitch maneuvers. Vanguard TV-3BU only reached an altitude of 6.1 km (3.8 mi), the goal was 3,840 km (2,390 mi).