Vanguard (rocket) - Overview

Overview

In 1955, the USA announced plans to put a scientific satellite in orbit for the International Geophysical Year (IGY) in 1957-1958. The goal was to track the satellite as it performed experiments. At that time there were three possible candidates for the launch vehicle: The Air Force's SM-65 Atlas, a derivative of the Army Ballistic Missile Agency's SSM-A-14 Redstone, and a Navy proposal for a three-stage rocket based on the RTV-N-12a Viking sounding rocket.

The Army's Redstone-based proposal would likely be first ready for a first satellite launch. Its connection with German-born scientist Wernher von Braun, however, was a public relations risk. In any case, the Atlas and Redstone ballistic missiles were top-priority military projects, which were not to be slowed by pursuing a secondary space launch mission. Vanguard was a project of the Naval Research Laboratory (NRL), which was regarded more as a scientific than a military organization. This helped to emphasize the non-military goals of the satellite program. This was considered important, because a discussion of whether overflights of foreign countries by satellites were legal or illegal was to be avoided.

In August or September 1955, the DOD Committee on Special Capabilities chose the NRL proposal, named Vanguard, for the IGY project. The Martin company, which had also built the Viking, became prime contractor for the launch vehicle. The Vanguard rocket was designed as a three-stage vehicle. The first stage was a General Electric X-405 liquid-fueled engine (designated XLR50-GE-2 by the Navy), derived from the engine of the RTV-N-12a Viking. The second stage was the Aerojet General AJ10-37 (XLR52-AJ-2) liquid-fueled engine, a variant of the engine in the RTV-N-10 Aerobee. Finally, the third stage was a solid-propellant rocket motor. All three-stage Vanguard flights except the last one used a motor built by the Grand Central Rocket Company. Vanguard had no fins, and the first and second stages were steered by gimbaled engines. The second stage also housed the vehicle's telemetry system, the inertial guidance system and the autopilot. The third stage was spin stabilized, the spin being imparted by a turn-table on the second stage before separation.