Phase 2 EELV – An Old Configuration Option with New Relevance to Future Heavy Lift Cargo

In 2004, the Atlas program of Lockheed Martin created a vision for performance evolution of the Atlas V family focused on NASA growth missions, with performance options ranging up to 140t. The 5m diameter, 70t class Phase 2 Atlas Heavy, assuming dual RD-180s, was a key vehicle in this evolution. With Constellation, this configuration was put on the back burner, but there is now renewed interest with Augustine Commission identifying this vehicle on its short list of candidate Heavy Lift Launch Vehicles (HLLVs). With a dearth of publicly available data on this vehicle concept, this paper summarizes this configuration and its merits. The creation of United Launch Alliance has created important synergies with the availability of 5m tank hardware and production facilities from Delta IV, allowing ULA to incorporate the best of Atlas and Delta. The Phase 2 design leverages existing assets, including the Delta IV factory and the Atlas V launch pad, makes this a true EELV evolution. Newer upper stages alternatives now conceptually exist that might leverage NASA developments from the Constellation program to further enhance the Phase II EELV concept.