Anna

American earth geodetic satellite. Geodesy satellite built by Johns Hopkins University Applied Physics Laboratory (APL) for USAF, US Navy, US Army, NASA, USA. Launched 1962.

ANNA was a geodetic research satellite with the primary missions of measuring the strength and direction of the Earth's gravitational field, locating the center of the Earth's mass and marking off positions on the Earth.

ANNA weighed 160 kg, was 0.91m in diameter and was powered by a band of solar cells around its equator supported by nickel cadmium batteries. A broad band spiral antenna was painted on the sphere, and the instrument tray was centrally mounted on the inside. Named for Army, Navy, Air Force and NASA. its sponsors, ANNA was launched October 31, 1962. The satellite contained optical, radio ranging and radio Doppler instrumentation. The optical system was a high intensity optical beacon activated by programmed command to set off a series of 5 light flashes 5.6 seconds apart. These were photographed by ground stations. The Navy Doppler frequency system was also still operable on command. Despite deterioration of the satellite's solar cells by the artificial radiation belt, ANNA had provided a large amount of geodetic information and permitted highly accurate positioning of tracking stations relative to the center of the Earth. Findings of the Air Force flashing light and the Navy Doppler frequency measurement systems agreed to accuracies of 20 meters or better. The Army's radio-ranging system ceased operation in orbit too early to yield comparative data. Prime Contractor: The Johns Hopkins University Applied Physics Laboratory.