Architecture assessment of HLLV candidates

Results of an architecture study of four Heavy Lift Launch Vehicles (HLLV) families are summarized, with attention given to civil, commercial, military and Space Exploration Initiative (SEI) applications. The Mars Exploration architecture is used as the SEI model baseline, and the architecture of each vehicle family is analyzed with respect to ground processing, launch operations, on-orbit operations, mission performance, and cost. For lunar missions, a 70-t earth-to-orbit (ETO) vehicle is shown to have definite cost advantages, with only small operational disadvantages, if the lunar program is small or medium in size. For Mars, a comparison of 150-t and 250-t ETO vehicles shows that little operational advantage is gained by going to the 250-t size.