PAGEOS 1

PAGEOS 1 [NASA]

The PAGEOS (Passive Geodetic Earth Orbiting Satellite) spacecraft was a 30.48 m inflatable sphere, and had no instrumentation on board. It was the second (following GEOS 1) NASA satellite in the National Geodetic Satellites Program.

PAGEOS 1 was made up of 84 gores and 2 pole caps of 0.0127-mm aluminized mylar film. The gores were 48 m long with maximum width of 1.24 m and the pole caps were 1.02 m in diameter. It was more or less a copy of the Echo 1 passive comsat. The primary purpose of the satellite was to provide a tracking target for geodetic purposes. It had a specular reflectance of 0.862, and a diffuse reflectance of 0.029, providing a reflecting light source whose brightness was relatively independent of observer-satellite-sun phase angle. The surface was also 97% reflectant for microwave energy in the range from 17 to 4E⁵ kHz.

The launch, orbit, separation, inflation and initial operation were nominal, with more than 40 ground stations participating in the observation program. The orbit was generally considered too high for drag-density study, although some work was done in this area by the Smithsonian Astrophysical Observatory.

PAGEOS operated for 9 years. It partly disintegrated in July 1975, which was followed by a second break-up that occurred in January 1976 resulting in the release of a large number of fragments. Most of these re-entered during the following decade. The last major fragment reentered on 2 September 2016.