I recently coined the phrase Flexible Path to the Moon for an approach to exploration and development of space by astronauts and robots intended to reach the Moon using gradual, incremental steps that are useful and sustainable. This phrase is based on the Augustine Committee's "Flexible Path to Mars". In fact the Flexible Path to the Moon uses the early destinations of the Augustine Flexible Path to Mars: Earth-Moon Lagrange points and lunar orbit. It also uses various Earth orbits used by satellites will be accessible if these other destinations are accessible. However, the Flexible Path to the Moon takes more time to build infrastructure, establish commerce, gather science data, and develop various operational capabilities at these initial beyond-LEO destinations. As implied by the Augustine Committee, such steps can and ultimately should be a solid foundation for additional exploration at more distant deep space destinations like Earth-Sun Lagrange points, asteroids, and eventually Mars. However, the intent of the Flexible Path to the Moon is to first use that foundation to explore and develop the lunar surface for science, commerce, and security, while at the same time making more distant exploration more achievable through the use of lunar resources.
There are three steps in the Flexible Path to the Moon, with potential overlap between steps. Each step might take a considerable number of years, depending on the available budget. The steps are to establish a foothold in low-Earth orbit that leads to the next steps, to go to beyond low-Earth orbit to lunar orbit, Earth-Moon Lagrange points, and beyond-LEO satellite orbits for immediate practical benefits and to enable later exploration, and finally to reach, explore, and develop the lunar surface.
With the recently-announced 2011 NASA budget proposal, It may be useful to consider how the Flexible Path to the Moon might fit in that proposal. The 2011 NASA budget contains many changes. Very briefly, it cancels the Constellation program intended to support the space station and eventually reach the Moon's surface. It replaces Constellation with human spaceflight precursor robotic missions, a general space technology program, an exploration technology demonstration program, a heavy lift and propulsion effort, a more fully used International Space Station that will be maintained longer and expanded, additional funding for the existing COTS commercial cargo program to account for the more intensely used space station, a program to encourage commercial crew services to the space station, and a considerably expanded Earth observation program.
Although there is some confusion about what the physical destinations will be for the astronaut exploration component of NASA, all indications are that something like the Flexible Path to Mars is planned. Like the Flexible Path to the Moon, this path might include visits to nearby destinations in space as well as the lunar surface. However, it probably would not develop as much infrastructure and capability at these destinations as would the Flexible Path to the Moon. Instead, it would reach more distant deep space destinations before the lunar surface, and would move as quickly as possible to Mars. There is little information yet about what we would do at various destinations. Would the missions be focused on science? Resources? Exploration? No specific exploration hardware or missions have been spelled out. Some details may come soon, and others may have to wait years for results from robotic precursor and technology demonstration missions.
I would argue that the Flexible Path to the Moon is more achievable and affordable than the Flexible Path to Mars, and is also more rewarding. Even though it seems likely that the Flexible Path to the Moon will not be taken, it could be taken, given the decision to do so. The 2011 NASA budget could, with some minor changes in emphasis, begin to implement the Flexible Path to the Moon. That opportunity will be the subject of later posts.