Powered Flight of Electron Cyclotron Resonance Ion Engines on Hayabusa Explorer

TLDR

The electron cyclotron resonance ion engine offers long life and high reliability due to electrodeless plasma generation in both the ion generator and neutralizer. A new electric‑propelled delta‑V Earth gravity assist scheme using high‑specific‑impulse propulsion was employed to transfer from a terrestrial orbit to an asteroid‑based orbit. Four μ10 ion engines, each providing 8 mN thrust, 3200 s Isp, and 350 W power, propelled Hayabusa from launch in 2003, enabling continuous acceleration after conditioning, a 0.86–1.7 AU transfer in 2005, rendezvous with, landing on, and lift‑off from Itokawa, and delivering a total ΔV of 1400 m/s over 25,800 h while consuming 22 kg of xenon.

Abstract

The electron cyclotron resonance ion engine has long life and high reliability because of electrodeless plasma generation in both the ion generator and the neutralizer. Four μ10s, each generating a thrust of 8 mN, specific impulse of 3200 s, and consuming 350 W of electric power, propelled the Hayabusa asteroid explorer launched on May 2003. After vacuum exposure and several baking runs to reduce residual gas, the ion engine system established continuous acceleration. Electric propelled delta-V Earth gravity assist, a new orbit change scheme that uses electric propulsion with a high specific impulse was applied to change from a terrestrial orbit to an asteroid-based orbit. In 2005, Hayabusa, using solar electric propulsion, managed to successfully cover the solar distance between 0.86 and 1.7 AU. It rendezvoused with, landed on, and lifted off from the asteroid Itokawa. During the 2-year flight, the ion engine system generated a delta-V of 1400 m/s while consuming 22 kg of xenon propellant and operating for 25,800 h.