Landmark Navigation Studies and Target Characterization in the Hayabusa Encounter with Itokawa

On 12 September 2005, the Japanese Hayabusa spacecraft arrived at the asteroid 25143 Itokawa. Due to Itokawa’s small size (~550 meters) and low gravity, the spacecraft did not orbit, but hovered near each of two stations on a line between the asteroid and Earth. It remained at the “Gate Position” at a range of about 18 km until September 30, and then shifted to the “Home Position” at a range of about 7 km. Between October 8 and 28, it made several excursions to higher phase locations to obtain varying illumination conditions, and away from the equator to obtain polar data. On November 4, 9 and 12, the spacecraft made approaches to the asteroid in preparation for touchdowns on November 20 and 26.