Seminars

As evidenced by the Global Exploration Roadmap, international interest exists in a new era of human exploration of the solar system. From among several different efforts, NASA is currently focused on positioning and maintaining an inhabited facility in a long-term and relatively stable orbit in the lunar vicinity. The Earth-Moon libration points offer many options and, currently, one orbit of interest for a habitat spacecraft in cislunar space is a Near-Rectilinear Halo Orbit (NRHO). Near Rectilinear Halo Orbits are members of the Earth-Moon L1 or L2 halo orbit families and are characterized by favorable stability properties. As such, they are strong candidates for a future habitat facility in cislunar space. This type of trajectory was first identified in the simplified representation of the Earth-Moon system—the circular restricted three-body problem. However, the motion persists in a higher fidelity model, and thus, supports long-term mission scenarios for spacecraft – eventually crewed vehicles – in orbits near the Moon. Such orbits are proposed for both storage of propellant and supplies for lunar missions, as well as potential locations for a space-based facility to support future crewed and robotic translunar missions. Beyond the nearvicinity of the Moon itself, however, applications are being pursued throughout an expanded Earth neighborhood within lunar orbit. Thus, further development of an available transport network in cislunar space is valuable. Transfers that require impulsive maneuvers are available as well as continuous low-thrust options. For actual mission implementations, however, transfers into such orbits as well as escape predictions and stationkeeping strategies must also be demonstrated.