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Each spacecraft was a large metallized balloon designed to act as a passive communications reflector to bounce signals transmitted from one point on Earth to another. Following the failure of the launch vehicle carrying Echo 1, Echo 1A (commonly referred to as Echo 1) was successfully orbited on 12 August 1960, and was used to redirect transcontinental and intercontinental telephone, radio, and television signals. It also provided data for the calculation of atmospheric density and solar pressure due to its large area-to-mass ratio.
Orbiting once every 90 minutes, Echo 1A was visible to the unaided eye over most of the Earth and was probably seen by more people than any other man-made object in space.
Echo 2 was launched on 25 January 1964 and continued the passive communications experiments. Scientists also used it to investigate the dynamics of large spacecraft and for global geometric geodesy. Echo 1A reentered the atmosphere on 24 May 1968 followed by Echo 2 on 7 June 1969.