The World's Oldest Satellite Still in Orbit

Vanguard I Launch, March 1958
Vanguard I Launch, March 1958

Vanguard I, the world's longest orbiting man made satellite, built by the Naval Research Laboratory (NRL) and launched at Cape Canaveral, Florida, in 1958, marked its 40th year in space on March 17, 1998. In the years following Vanguard's launch, the small satellite has made more than 158,061 revolutions of the earth and traveled over 4.59 billion nautical miles.

The first solar-powered satellite, Vanguard I was the second artificial satellite successfully placed in earth orbit by the United States. (Vanguard predecessors, Sputniks I and II and Explorer I, have long since fallen out of orbit.) Fifteen cm in diameter and weighing just 1.4 kg, Vanguard was described by then-Soviet Premier Nikita Khrushchev as "the grapefruit satellite."

As part of the scientific program for the International Geophysical Year (1957-58), NRL was officially given the responsibility of placing an artificial satellite with a scientific experiment into orbit around the earth. Designated Project Vanguard, the program was placed under Navy management and DoD monitorship.

NRL's Space Technology Center was responsible for developing the launch vehicles; developing and installing the satellite tracking system; and designing, constructing, and testing the satellites. The tracking system was called Minitrack. The Minitrack stations, designed, built, and initially operated by NRL, were along a North South line running along the east coast of North America and the west coast of South America. Minitrack was the forerunner of another NRL-developed system called NAVSPASUR, which is operational today and a major producer of spacecraft tracking data.

In late 1958, responsibility for Project Vanguard was transferred to NASA. Some of NRL's Project Vanguard members joined NASA, forming the nucleus of the Goddard Space Flight Center. The Space Technology Center at NRL was redesignated the Naval Center for Space Technology and given overall responsibility to conceive, develop, and demonstrate space and aerospace systems and technology to meet Navy, Department of Defense, and National needs.

In the years following Project Vanguard's transfer to NASA, NRL rebuilt their spacecraft technology capability and have developed some 87 satellites over the past 40 years for the Navy, DoD, and NASA. NRL's relationship with NASA is still very active; for example, NRL is currently developing the Interim Control Module for NASA's International Space Station.

Vanguard met 100 percent of its scientific objectives, providing a wealth of information on the size and shape of the earth, air density, temperature ranges, and micrometeorite impact. It proved that the earth is pear-shaped, not round; corrected ideas about the atmosphere's density at high altitudes and improved the accuracy of world maps.

Vanguard I Satellite on display at the Smithsonian Institution's National Air and Space Museum
Vanguard I Satellite on display at the Smithsonian Institution's National Air and Space Museum

NRL space scientists say that the Vanguard I program introduced much of the technology that has since been applied in later U.S. satellite programs, from rocket launching to satellite tracking. For example, it proved that solar cells could be used for several years to power radio transmitters. Vanguard's solar cells operated for about seven years, while conventional batteries used to power another onboard transmitter lasted only 20 days.

Although Vanguard's solar-powered "voice" became silent in 1964, it continues to serve the scientific community. Ground-based tracking of the satellite provides data concerning the effects of the sun, moon and atmosphere on satellite orbits.