Rendezvous to asteroid with highly uncertain ephemeris: Hayabusa2's Ryugu-approach operation result

This paper describes the guidance and navigation technique used by Hayabusa2 for the asteroid rendezvous operation to reach Ryugu. The operation results, including the achieved guidance and navigation performance, are also summarized. Multiple assessment and navigation teams worked closely to provide reliable navigation solutions with a short solution delivery cycle. Although the uncertainty of the Ryugu's ephemeris was considerable before Hayabusa2's arrival, a combination of radiometric-optical hybrid navigation and a stochastic-constrained optimum guidance method was able to achieve an accuracy of less than 100 m and 1 cm/s, and the arrival was precisely timed.