The lunar orbit version required an Agena stage to provide the delta-V for lunar orbit insertion and trans earth injection. The 1.52 m-diameter Agena was enclosed in an inverted conical fairing to both transmit thrust loads to the Gemini and provide thermal protection during the coast to the moon. Alternatively, a propulsion module based on a repackaged Apollo Service Module propulsion system, as had been proposed two years earlier for a lunar-landing version of Gemini, could be used. This raised the translunar injection mass of the spacecraft to 11,182 kg, well above the capability of a Saturn IB or Titan 3C, but only a quarter that of a Saturn V. The launch vehicle was unspecified, but could only have been a Saturn V used on an early test mission. The mission profile would have involved a 68 hour flight from low earth orbit to lunar orbit, a 24 hour lunar mapping mission in a 10 nm x 80 nm lunar orbit, and a 68 hour return flight. The scientific equipment would consist of a modest camera array installed in the nose of the spacecraft. This consisted of a long focal-length telescope, to which were attached two narrow-field stereo mapping cameras, a wide field mapping camera, a panoramic camera, and two 16 mm film cameras. The film was not accessible by the astronauts, being stored in a film vault shielded against radiation in the nose of the spacecraft. The camera compartment would protrude from the stub nose of the Gemini after parachute deployment.
The manned portion was the same as the circumlunar version, a modified earth-orbit Gemini. The aft modules would be retained, but with the retrorockets removed. The retro module space would be used to install Apollo-type lunar distance communications, navigation, and test equipment. Deployable DSIF omni-directional and parabolic antennae would deploy from the aft modules to support lunar-distance communications. To handle re-entry from lunar distances, several modifications were necessary. The capsule's heat shield would be beefed up, and the Rene 41 corrugated shingles of Gemini's skin would be replaced with ablative shingles. The load of attitude control propellant for the capsule's reaction control system was substantially increased. Additional strap-down gyros and solar sensor packages would be added to provide navigation system redundancy. The ejection seats would be deleted and a Mercury-style launch escape tower added. The then-planned Rogallo wing recovery system would be used to glide to the Gemini to a runway landing on US territory after return from the moon. To handle the scientific payload, a camera compartment was added to the nose below the parachute/Rogallo wing housing. The Gemini spacecraft modified in this way had on on-orbit mass of 3955 kg as compared to the 3207 kg of the earth-orbit version.
Crew Size: 2. Habitable Volume: 2.55 m3.
Gross mass: 11,182 kg (24,652 lb).