An initial study of orbital transfer vehicle in reference mission scenario of human lunar exploration with manned station at Earth-Moon libration point

International Space Exploration Coordination Group (ISECG) released reference mission scenario ultimately conducting the manned exploration to Mars, which is known as the Global Exploration Roadmap (GER). On the course of attaining the ultimate goal, several preparatory exploration missions might be required. One of the most promising intermediate destinations is Earth-Moon Lagrange Points (EMLs) which have unique characteristic of gravitational equilibrium. Among the 5 EMLs, EML2 is considered as the most superior position not only as the staging station for further solar system exploration but also as the base camp for lunar far side exploration. This paper gives the results of an initial study of Orbital Transfer Vehicle (OTV) in reference mission scenario of Lunar Exploration commanded by crew staying at EML2 Manned Station. Assuming that SLS and H-X (Japanese next Flagship Launch System) are utilized as launchers, sizing study of OTV has been conducted. Cargo Supply Ship is also sized to maximize cargo mass to be transferred to EML2 Manned Station.