The small Minerva robot is first and foremost an ingenious concept thought up by JAXA engineers for the Hayabusa mission, which had to meet a new challenge. They had to design a system for Minerva to move about on the Itokawa asteroid. The gravity at the surface is insufficient to provide enough friction for the wheels to be able to move forward. Minerva had to move by hopping, the hops being accurately calculated to avoid accidentally hopping into orbit or even leaving the ground permanently!
Although the Minerva robot was successfully released on 12 November 2005, it failed in its attempt to set itself down on the surface of the Itokawa asteroid. The reason for the failure was that Minerva was released at a higher altitude than intended because at the moment the release command was received, the Hayabusa probe was ascending in an altitude correction manoeuvre.