The Vanguard rocket[1] was intended to be the first launch vehicle the United States would use to place a satellite into orbit.

Of the eleven Vanguard rockets which the project attempted to launch, three successfully placed satellites into orbit.

Vanguard rockets were an important part of the Space Race between the United States and the Soviet Union.

In 1955, the United States announced plans to put a scientific satellite in orbit for the International Geophysical Year (IGY) in 1957–1958.

[8][4] In any case, the Atlas and Redstone ballistic missiles were top-priority military projects, which were not to be hindered by pursuing a secondary space launch mission.

[9] Milton Rosen's Vanguard was a project at the Naval Research Laboratory (NRL), which was regarded more as a scientific than a military organization.

[11] In August or September 1955, the DOD Committee on Special Capabilities chose the NRL proposal, named Vanguard, for the IGY project.

[15] On 6 December 1957, the US Navy launched Vanguard TV-3 rocket, carrying a 1.5-kilogram (3.3 lb) satellite, from Cape Canaveral.

The satellite was exploded from the top of the rocket, landed in bushes near the pad, and began transmitting signals, leading New York Journal-American columnist Dorothy Kilgallen to remark "Why doesn't somebody go out there, find it, and shoot it?

[17] Investigation into the accident concluded that inadequate fuel tank pressure had allowed hot exhaust gases to back up into the injector head and destroy it, causing complete loss of engine thrust.

Pad crews hastened to repair the damage done to LC-18A by Vanguard TV-3's explosion, and in the third week of January 1958, the job was completed.

The second stage had also been sitting on the pad with a full load of nitric acid for several weeks, which eventually corroded the fuel tank and valves.

By that time, however, the Army's Juno (Jupiter-C) had already launched the United States' first satellite, Explorer 1.

That last mission was designated Vanguard TV-4BU, because it used a remaining test vehicle, which had been upgraded with a new third stage, the Allegany Ballistics Laboratory X-248A2 Altair.