Human exploration of the Moon, Near-Earth Asteroids, and Mars using staging from Earth-Moon L-2 orbits and phasing orbit rendezvous

This work extends the trajectory concepts for human exploration reported at the 2014 IAC in Toronto. The advantages of using an Earth-Moon L-2 (EM-L2) halo orbit for accessing all parts of the Moon, and for departures using powered lunar and Earth gravity assists to explore near-Earth objects, Mars, and Phobos will be demonstrated. Different types of halo orbits will be explained, including near rectilinear halo orbits (NRHOs) and the small-amplitude halo orbits studied earlier, as well as lunar distant retrograde orbits. Three communications satellites spaced around an NRHO, along with Earth, could provide continuous communication for the whole Moon and throughout cislunar space. The basic exploration idea is to use an Interplanetary Transportation Vehicle (ITV) that would stay in high-energy orbits when near the Earth, parked in an EM-L2 (or other) orbit between missions for reusability. For going to a new destination, the ITV would be placed in highly elliptical Earth orbits (HEOs) following a lunar powered swingby after departure from the EM-L2 orbit, and before the powered “Oberth� perigee maneuver performed at the right time to depart for the interplanetary destination. This could be done robotically, without a crew. HEOs enable multiple opportunities to rendezvous with the ITV from Earth with capabilities significantly less than the Orion capsule and heavy launch vehicles (not necessarily the SLS); this provides a robust method of transferring astronauts, fuel, and supplies to the ITV shortly before the interplanetary departure. The HEOs serve as phasing orbits, to achieve the right direction and time for the ITVs hyperbolic departure following the Oberth maneuver. Hybrid (high and low thrust), and high-thrust trajectories to rendezvous with asteroid 2000 SG344 in 2029, that could serve as a shorter precursor mission before going to Mars, will be presented. At Mars, staging is also possible for the ITV, from an elliptical Mars orbit, perhaps with a period of 10 days, from which astronauts could be ferried to Phobos or the Martian surface with a pre-positioned Mars vehicle designed for this, possibly using fuel generated on Mars. The apoapse of the ITV, uncrewed while the astronauts explore Phobos or Mars, can be raised robotically with relatively small maneuvers to a high-enough distance where solar perturbations can change the line of apsides to the direction needed for the departure back to Earth, then lowered back to the 10-day orbit before the return departure.