Beacon was an International Geophysical Year (IGY) satellite program developed by the National Advisory Committee for Aeronautics Space Vehicle Group at Langley under aeronautical engineer William James O'Sullivan, Jr. O'Sullivan held the belief that measuring the air density at orbital altitudes would be of critical importance to a space agency and that a simple balloon satellite, several meters in diameter, would be well suited to the task[1] as their relatively large size and low mass make them especially sensitive to air drag effects.

O'Sullivan's balloon satellite would accomplish that purpose,[1] as, once in orbit, it would be as bright as a third or fourth magnitude star,[3] enabling easy optical and photographic tracking.

"[1] Beacon was an uninstrumented, inflatable 3.66 meter (12 ft) diameter sphere made of laminated mylar polyester film, 25 micrometers in thickness, and coated on both sides with an 11 micrometer-thick layer of aluminum foil.

The guidance and control system then failed, causing the upper stages to fire in the wrong direction, and Beacon 2 fell short of orbit.

On April 22, 1958, before the House Select Committee on Science and Astronautics, NACA Director Hugh Dryden explained, among many other things, how large aluminized balloons could be inflated in orbit and used for communication tests.

O'Sullivan elaborated on this point, impressing the Congressmen by inflating a full-size Beacon satellite and asserting that much larger balloon spacecraft could easily be developed.