Dual Mission Scenarios for the Human Lunar Campaign - Performance, Cost, and Risk Benefits

NASA's future human lunar campaign faces significant performance, cost, and risk challenges. These include: providing access to large portions of the lunar surface for expanded science and exploration opportunities within the performance constraints of the integrated transportation system; minimizing the annual cost of the lunar campaign; minimizing operational risk, including probability of loss of mission (PLOM) and probability of loss of crew (PLOC). Innovative lunar operations scenarios that address these challenges are potentially feasible based on the concept of dual, sequential missions utilizing a common crew and a single Ares I/crew exploration vehicle (CEV). Dual mission scenarios possible within the scope of baseline technology planning include outpost-based sortie missions, dual sortie missions, and enhanced outpost deployment. Additional mission scenarios are potentially possible with the development of advanced capabilities. These include expanded lunar abort modes and lander reusability options. Top-level benefits of these dual mission scenarios may be estimated by comparison with the Constellation Program reference two-mission-per-year lunar campaign. The primary performance benefit is substantially improved surface access and an increase in payload mass to the lunar surface for Mission B of the two-mission sequence. The cost benefit is the accomplishment of Mission B with a "single launch solution" because no Ares I launch is required. Compared with other single launch solutions that have been proposed, this option provides an additional cost benefit because it does not require the human rating of the Ares V. The PLOM for dual mission scenarios is significantly lower because Mission B does not require the successful launch of two launch vehicles and an orbital rendezvous in time for the translunar injection (TLI) window. Cumulative risk to the crew is lower because crew exposure to Earth launch risks and Earth entry risks is reduced versus comparable Constellation Program reference two-mission-per-year scenarios.