LOW-THRUST TRAJECTORY DESIGN AND OPERATIONS OF PROCYON, THE FIRST DEEP-SPACE MICRO-SPACECRAFT Stefano Campagnola (1) , Naoya Ozaki (2) , Yoshihide Sugimoto (3) , Chit Hong Yam (3) , Hongru Chen (4) , Yosuke Kawabata (5) , Satoshi Ogura (5) , Bruno Sarli (5) , Yasuhiro Kawakatsu (3) , Ryu Funase (2) , and Shinichi Nakasuka (2) (1) ISAS/JAXA, Yoshinodai 3-1-1, Sagamihara, Kanagawa 252-5210, Japan, +81 70 6912 1162, stefano.campagnola@jaxa.jp (2) The University of Tokyo, Japan (3) ISAS/JAXA, Japan (4) Kyushu University, Japan (5) The Graduate University for Advanced Studies,, Japann Abstract: PROCYON is the first deep-space micro-spacecraft; it was developed at low cost and short time (about one year) by the University of Tokyo and JAXA, and was launched on December 3rd, 2014 as a secondary payload of the H-IIA launch of Hayabusa2. The mission primary objective is the technology demonstration of a micro-spacecraft bus for deep-space exploration; the second objectives are several engineering and science experiments, including an asteroid flyby. This paper presents PROCYON high-fidelity, very-low-thrust trajectory design and implementation, subject to mission and operation constraints. Contingency plans during the first months of operations are also discussed. All trajectories are optimized in high-fidelity model with jTOP, a mission design tool first presented in this paper. Following the ion engine failure of March 2015, it was found the nominal asteroid could not be targeted if the failure was not resolved by mid-April. A new approach to compute attainable sets for low-thrust trajectories is also presented. Keywords: PROCYON, micro-spacecraft operation, low-thrust 1. Introduction PROCYON [1] is a micro-spacecraft by the University of Tokyo and ISAS/JAXA that was launched on Dec 3rd, 2015. PROCYON is the world’s first deep-space micro-spacecraft, and the world’s first deep-space mission by an university. The mission primary objective is the technology demonstration of a micro-spacecraft bus for deep-space exploration; secondary objectives include a number of engineering and science experiments, most of which have been successfully executed. One secondary objectives has not been achieved: the flyby of the binary asteroid 2000 DP 107, which is enabled by low-thrust orbit control and an Earth flyby, cannot currently be attained because of a failure of the Ion Engine System (IES). Despite this accident, PROCYON demonstrated that deep space exploration by a micro-spacecraft is feasible, and especially, that such a spacecraft can be developed in a little more than a year. Short development times enable frequent and low-cost access to deep-space exploration, with a tremendous impact to the space community, for both scientists and engineers. For this reasons, in the last year both ESA, JAXA and ESA released announcements of opportunities for interplanetary cubesat; the first interplanetary cubesat MARCO will be launched in 2016. Deep-space micro-spacecraft design and operation present many challenges. Efficient, miniaturized, 1