American manned spacecraft module. Study 1961. The retrograde module supplied the velocity increments required during the translunar portion of the mission up to a staging point approximately 1800 m above the lunar surface.
Status: Study 1961. Thrust: 117.86 kN (26,495 lbf). Gross mass: 24,393 kg (53,777 lb). Unfuelled mass: 2,833 kg (6,245 lb). Height: 5.00 m (16.40 ft). Diameter: 6.61 m (21.68 ft).
Engine thrust could be throttled down to 1201 kgf.