[Illustration: 68. Three-stage Vanguard launch vehicle boosts the
second American satellite into Earth-orbit, March 17, 1958.]
Standing 21.6 meters (70.8 feet) high and weighing more than 10,000
kilograms (20,000 pounds), the Vanguard launch vehicle successfully
orbited three satellites. The first was _Vanguard 1_, launched on March
17, 1958.
The rocket has three stages. The first-stage motor, burning kerosene and
liquid oxygen, operated for 2 minutes and 20 seconds. The second stage
carried the vehicle to an altitude of 210 kilometers (130 miles),
propelled by white-fuming nitric acid and unsymmetrical
dimethylhydrazine (UDMH). With propellants exhausted, the upper stages
then coasted to 480 kilometers (300 miles) above the surface of the
Earth where the solid-propellant third-stage motor fired to place the
satellite into orbit.
The Vanguard was designed and built by the Martin Company for the U.S.
Naval Research Laboratory.