Sample Collection Methodology
Artist depiction of Hayabusa docked with asteroid Itokawa to collect surface samples.
(Artwork courtesy of JAXA)
The asteroid Itokawa is so small and the surface gravity is so low, the spacecraft wasn't able to really land on it; instead, it “docked” with the asteroid. Prior to the Hayabusa mission, we didn’t know if the surface was composed of hard rock or soft dirt. Any pressure, or force put on the asteroid in order to dig into the surface, would have pushed the spacecraft away.
The Hayabusa rendezvous spacecraft carried a horn that was designed to be brought up to the surface of Itokawa as it made a close approach of the asteroid. During each of these touch-and-go “landings”, a 5-gram projectile was to be fired at the surface at a velocity of a 300 meters per second in order to blast a small quantity of material from the surface (See diagram below - A). The surface dust and fragments from the impact were then captured by the horn (B) and funnelled into a sample container (C).
Diagram showing the sample collection process during the Hayabusa mission. A projectile is fired at the asteroid (A and B) and the debris is then collected (C).
(Photo courtesy of JAXA)