Cooperative scenarios for human exploration beyond Low Earth Orbit

There is an international need to define a concrete strategy and plan to implement that strategy for the initial human exploration missions beyond Low Earth Orbit (LEO). Across all stakeholders, there is a growing consensus that the long term objective of global human space exploration is the long duration presence of people on the Martian surface. Along the pathway between current activities in LEO and eventual Mars outposts are a variety of preparatory exploration missions and intermediate goals. Over the last decade several different initial steps along these pathways beyond LEO have been proposed. It is important to build international consensus on such a plan soon because future missions require near-term investments for new capabilities with no single nation committing resources to achieve all the steps of an ambitious program on its own. The goal of this work is to enumerate and evaluate scenarios for cooperative missions beyond LEO that achieve incremental development of human exploration capabilities. Towards the goal of generating scenarios for cooperative missions beyond LEO, proposed missions and capabilities from a variety of international actors have been assessed. Presented in this paper are results of a survey of proposed missions and a series of interviews with industry experts knowledgeable about both the technical and geopolitical issues in forging a sustainable path towards Mars. There are four realistic proposals for initial human exploration beyond LEO: a cis-Lunar habitat, asteroid redirect, Mars flyby, and a Lunar surface sortie. In the absence of top-down agreements, such as those governing the International Space Station, that specify partnership responsibilities and privileges, ad-hoc exchanges within individual development projects or for specific mission capabilities is most likely to facilitate international cooperation in the coming years. General LEO transportation logistics and habitation functions are shared by many actors and allow for exchange of services and utilization of exploration assets if designed into the critical path. Given the early stage of readiness, it is possible that subsystem-level coordination could be pursued for an advanced habitation element. Other technologies are either niche (robotics) or have national sensitivities (in-space propulsion) that make them less desirable for subsystem-level coordination.