Mission extension of Hayabusa2 for planetary defense, small body flyby and rendezvous sciences

Hayabusa2, the second Japanese asteroid sample return mission, successfully returned to Earth on December 6, 2020 with primordial samples of the carbonaceous asteroid Ryugu. After releasing the sample return capsule toward Earth, the Hayabusa2 spacecraft commenced the new mission to two new asteroids by taking advantage of the remaining space asset that was fully healthy state with approximately half of the fuel remaining. This mission extension, named as “Hayabusa2#” or “Hayabusa2-SHARP” (Small Hazardous Asteroid Reconnaissance Probe), aims at visiting two asteroids, Torifune (formerly designated as 2001 CC21) to fly-by in 2026, and 1998 KY26 to rendezvous in 2031 to contribute to science and technology of the planetary defense, flyby science of a small body, and rendezvous science of a small fast-rotator suspected dark-comet. This paper describes the mission plan, technical challenges and ongoing development status of the Hayabusa2# mission.