The KH-3, or Keyhole-3, represented the third iteration within the Corona program aimed at developing optical reconnaissance satellites, all launched under the Discoverer name. Enhanced with the C''' (Corona triple-prime) single panoramic camera, manufactured by Itek Corporation, the KH-3 payload offered improved imaging capabilities. With an f/3.5 aperture and a 61 cm focal length, the C'''-camera provided a ground resolution of 7.5 meters, enhancing image clarity. Operating atop the Agena-B upper stage for orbital maneuvering, the satellite facilitated attitude control during its mission. Upon completion, the film return capsule employed its own solid-fuel retro motor for deorbiting, with mid-air recovery facilitated by specialized aircraft.

OSCAR 1 was a quasi-rectangular box about 30 x 25 x 12 cm. The two approximately square sides were slightly curved, but were concentric with each other. One was slightly smaller than the other. A monopole transmitting antenna about 60 cm long extended from the center of the convex surface of the larger square. Reflective striping was applied for temperature control.