Mission Analysis for the EM-1 CubeSats EQUULEUS and OMOTENASHI

Abstract

OMOTENASHE and EQUULEUS are two 6-U CubeSats by JAXA and The University of Tokyo to be launched in 2019 onboard of NASA's Exploration Mission 1. This paper presents the nominal trajectories and an overview of the mission analysis work and approaches. EQUULEUS trajectory exploits the Earth -Sun -Moon dynamics to capture the spacecraft into a libration orbit around the Earth -Moon L2 point, using only -10 m/s of deterministic Av. Mission analysis cost and complexity, however, are driven by the statistical maneuvers because of the expected limited performances in orbit determination (because of limited ground station availability) and execution errors. OMOTENASHE mission analysis requires multiple iterations where the robustness to errors is evaluated over the design space. It is found that the spacecraft should approach the Moon with a shallow flight path angle of about -5°, avoid crater rims and mountains, and start the free fall at about 130 m height. For both missions, the initial week of operations, including Avl execution, is critical, and ground station support is being negotiated by the teams with JAXA and with international partners.