This NASA report reviews the various moon surface design reference missions developed as representative scenarios that could occur in a human lunar return. The approaches have been divided into two broad categories: a seven day short stay mission with global capabilities and a longer extended duration stay of 28 days which is limited to the lunar poles as a landing zone. The surface elements, trade studies, traverses, concept of operations and other relevant issues and methodologies will be presented and discussed in the context and framework of the HAT ground rules and assumptions which are constrained by NASA's available transportation systems.
Since 1969, NASA has conducted numerous internal studies and chartered 24 blue ribbon panels to assess future human space flight strategy, and exploration concepts and technologies. Following the cancellation of NASA's Constellation program in 2010, the most current instantiations of these groups examined a broad trade space of program strategies and technical approaches in an effort to meet priorities from the White House, Congress, and other stakeholders. In light of findings that its Constellation program was "pursuing goals that do not match allocated resources" (Augustine et al), new affordability options were examined. A major conclusion was that the NASA Human Space Flight (HSF) architecture must provide the flexibility to accommodate technical, programmatic, economic and political dynamics while enabling a safe, affordable and sustainable human space exploration program.
In order to do a comprehensive assessment of all DRM options that are possible, the Lunar Destination Team pursued a six dimensional matrix which covers all options whether they are desirable or feasible or not. Then through a process of logical analysis the trade tree was trimmed down by eliminating branches with obvious inconsistencies. What remains is a drastically reduced trade space which can then be used as the basis for comparison to missions already flown or for future DRM studies and further detailed analysis by "drilling down".