NASA’s Science Mission Directorate (SMD) has been entrusted the responsibility of establishment and implementation of a Robotic Lunar Exploration Program (RLEP); Goddard Space Flight Center (GSFC) has lead Center responsibility for managing and executing the program. The Robotic Lunar Exploration Program (RLEP) is expected to execute a series of robotic missions to the Moon, starting in 2008, in order to pave the way for human exploration missions to the Moon and, ultimately, to Mars and beyond.
The role of the RLEP is to ensure that all lunar flight missions are integrated into a program in a manner that allows them to achieve mission success, and support the larger goal of human exploration. For planning purposes, each flight mission is constrained to Discovery-class program resources (full cost, full lifecycle, including instruments, spacecraft, launch vehicle, ground systems, and mission operations), to be developed in less than four years. While the first flight mission will be purely orbital (i.e. the 2008 Lunar Reconnaissance Orbiter, hereafter LRO), subsequent missions may include surface elements (landed, or impacted), as required to best provide required measurements, validation of technologies, and risk mitigation for follow-on human missions. However, it is possible that each flight mission will include an orbital element, if for no other reason than to provide a platform for payload delivery and/or communications back to Earth.