Project Vanguard
In response to the launch of Sputnik 1 on 4 October 1957, the U.S. restarted the Explorer program, which had been proposed earlier by the Army Ballistic Missile Agency (ABMA).
Privately, however, the Central Intelligence Agency (CIA) and President Dwight D. Eisenhower were aware of progress being made by the Soviets on Sputnik from secret spy plane imagery.
Just 15.2 cm (6.0 in) in diameter and weighing 1.4 kg (3.1 lb), Vanguard 1 was described by then-Soviet Premier Nikita Khrushchev as, "The grapefruit satellite".
Encouraged by conversations between Richard W. Porter of General Electric and Alan T. Waterman, Director of the National Science Foundation (NSF), Rosen on 27 November 1954, completed a report describing the potential value of launching an Earth satellite.
[4] As part of planning for the International Geophysical Year (1957–1958), the U.S. publicly undertook to place an artificial satellite with a scientific experiment into orbit around the Earth.
The Army Ballistic Missile Agency (ABMA) under Dr. Wernher von Braun had suggested using a modified Redstone rocket (see: Juno I) while the Air Force had proposed using the Atlas launch vehicle, which did not yet exist.
[8] After a delay due to the NRL changing the shape of the satellite from a conical shape,[9] the initial 1.4 kg (3.1 lb) spherical Vanguard satellites were built at the NRL, and contained as their payload seven mercury cell batteries in a hermetically sealed container, two tracking radio transmitters, a temperature sensitive crystal, and six clusters of solar cells on the surface of the sphere.
Minitrack was the forerunner of another NRL-developed system called NAVSPASUR, which remains operational today under the control of the Air Force and is a major producer of spacecraft tracking data.
The payload nosecone detached and landed free of the exploding rocket, the small satellite's radio beacon still beeping.
In late 1958, with responsibility for Project Vanguard having been transferred to NASA, the nucleus of the Goddard Space Flight Center was formed.
Despite being overshadowed by Sputnik 1, and having to overcome the widespread humiliation of its unsuccessful early attempts, the Vanguard Project eventually met its scientific objectives, providing a wealth of information on the size and shape of the Earth, density of air, temperature ranges, and micrometeorite impact.
Vanguard's solar cells operated for about seven years, while conventional batteries used to power another on-board transmitter lasted only 20 days.
Ground-based optical tracking of the now-inert Vanguards continues to provide information about the effects of the Sun, Moon, and Atmosphere of Earth on satellite orbits.
