Vanguard 1

Vanguard 1 is an American satellite that was the fourth artificial Earth-orbiting satellite to be successfully launched, following Sputnik 1, Sputnik 2, and Explorer 1. it was launched 17 March 1958. Vanguard 1 was the first satellite to have solar electric power.

Vanguard 1 was designed to test the launch capabilities of a three-stage launch vehicle as a part of Project Vanguard, and the effects of the space environment on a satellite and its systems in Earth orbit. It also was used to obtain geodetic measurements through orbit analysis. Vanguard 1, being small and light enough to carry with one hand, was described by the Soviet Premier, Nikita Khrushchev, as "the grapefruit satellite".

 Spacecraft design 
The spacecraft is a 1.46 kg (3.2 lb) aluminum sphere 6 inches (152 mm) in diameter, with antennae spanning 3 feet. It contains a 10 mW, 108 MHz transmitter powered by a mercury battery and a 5 mW, 108.03 MHz transmitter that was powered by six solar cells mounted on the body of the satellite. Six 30 cm (12 in) long antennas, 0.8 cm (0.31 in) diameter spring-actuated aluminum alloy aerials protrude from the sphere. The transmitters were used primarily for engineering and tracking data, but were also used to determine the total electron content between the satellite and the ground stations.

A backup version of Vanguard 1 is on display at the Smithsonian National Air and Space Museum, Steven F. Udvar-Hazy Center in Chantilly, Virginia.

Category:American satellites
Category:1950s in spaceflight
Category:1950s in the United States
Category:1958