Orbiting Geophysical Observatory Program Jackson, J. E. and Vette, J. I. OGO Program Summary, NASA SP-7601 of NASA refers to the six satellites launched by the United States that were in use from September 1964 to 1972, designed to study the Earth's magnetosphere.
The Orbiting Solar Observatory (abbreviated OSO) Program was the name of a series of American space telescopes primarily intended to study the Sun, though they also included important non-solar experiments.