Chapter 13 - Superior solar conjunction phase: Design and operations

Abstract

On November 23, 2018, the Hayabusa2 spacecraft entered in superior solar conjunction. Thus, the spacecraft, in hovering around Ryugu, was in the Sun's shadow as seen from Earth. It is the first time, that a spacecraft experiences solar conjunction while in hovering at a minor celestial body. The solar corona caused a 21-day disruption in the Hayabusa2 spacecraft-Earth communication link due to the signal noise. To cope with the inability to control the spacecraft from ground during the communication blackout, the ayu (sweetfish-shape) conjunction trajectory was operated to raise the altitude of the spacecraft from the nominal 20km distance (Home-Position) to a maximum safety altitude of ~109km. During the conjunction, the spacecraft was kept on the day-side of the asteroid and it returned at Home-Position after 38days (29th December 2018). In this chapter, a summary of the ayu trajectory design, navigation, and post-operation results are presented.