Hayabusa2 switches to cross-operation after ion-engine power fault

(SpaceEnergy) JAXA’s Hayabusa2 asteroid probe will use a cross-connected ion-engine configuration for trajectory control after a power-supply fault disabled the ion source of its remaining operational engine.

The Japan Aerospace Exploration Agency said Hayabusa2 began ion-propulsion trajectory control on 9 July after its successful 5 July fly-by of asteroid Torifune. The manoeuvres are required for a December 2027 Earth swing-by en route to asteroid 1998 KY26 in 2031.

Engine B initially operated normally, but suffered repeated discharges in mid-August. JAXA attempted the recovery technique used after similar events in 2021 and 2025, before determining in late August that the power supply’s current-delivery function for the ion source had failed.

Engine B had already been the spacecraft’s sole conventionally operated ion engine after degradation affected engines A, C and D.

JAXA subsequently tested combinations of surviving components and found it could operate an ion thruster using engine D’s ion source, engine B’s neutraliser and the surviving neutraliser-B function of the affected power supply. The agency plans to continue trajectory control with this cross-operation configuration while monitoring the propulsion system.

The architecture echoes the cross-operation technique used during the original Hayabusa mission’s return to Earth.

JAXA said degradation knowledge accumulated during Hayabusa2’s long-duration ion-engine operation has also informed the propulsion design for the DESTINY+ mission, currently planned for launch in fiscal 2028.