There were initially four major subcontractors—Bell Aerosystems (ascent engine), Hamilton Standard (environmental control systems), Marquardt (reaction control system) and TRW's Space Technology Laboratories (descent engine).
Inițial au existat patru subcontractori majori: Bell Aerosystems (motorul de ascensiune), Hamilton Standard (sistemele de control al habitatului), Marquardt (sistemul de control cu reacție) and Rocketdyne (motorul de coborâre).