MINERVA Mini-lander
Hayabusa carried a tiny mini-lander (weighing only 591 g (20.8 oz), and approximately 10 cm (3.9 in) tall by 12 cm (4.7 in) in diameter) named "MINERVA" (short for MIcro/Nano Experimental Robot Vehicle for Asteroid). An error during deployment resulted in the craft's failure.
This solar-powered vehicle was designed to take advantage of Itokawa's very low gravity by using an internal flywheel assembly to hop across the surface of the asteroid, relaying images from its cameras to Hayabusa whenever the two spacecraft were in sight of one another.
MINERVA was deployed on 12 November 2005. The lander release command was sent from Earth, but before the command could arrive, Hayabusa's altimeter measured its distance from Itokawa to be 44 m (144 ft) and thus started an automatic altitude keeping sequence. As a result, when the MINERVA release command arrived, MINERVA was released while the probe was ascending and at a higher altitude than intended, so that it escaped Itokawa's gravitational pull and tumbled into space.
Had it been successful, MINERVA would have been the first space hopper to see action. Instead it joins ranks with the hopper carried on the failed Phobos 2 mission, which also never saw use.
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