It’s happening right now. Two little robots bristling with sensors and cameras departed the Japanese spacecraft Hayabusa-2 at 11:06 p.m. yesterday and have begun their free-fall descent to the surface of Ryugu, a barren, rocky asteroid 0.6 miles (1 km) across some 200 million miles (322 million km) from Earth. Named MINERVA II-1A and MINERVA II-1B, they’ll land on the asteroid and explore its surface via a unique form of propulsion — hopping.
Being small, Ryugu has a very low surface gravity. If the Minervas (stands for Micro Nano Experimental Robot Vehicle for Asteroid) tried to move using wheels or treads, the push-back would launch the probes off the surface and into space. Instead, an internal rotating motor will make each rover hop from place to place. During each hop, the MINERVAs are expected to remain airborne for up to 15 minutes and move up to 50 feet (15-meters) horizontally across the surface. Picture a rabbit (about the same size as a MINERVA) taking a leap, tumbling and turning above the ground for 15 minutes before finally landing again in a new spot.
What we learn from the MINERVAs will provide pictures and context for the samples that will be picked up by the main spacecraft next year and returned to Earth in December 2020.
Stay in touch with the latest news about the spacecraft and the MINERVAs via Twitter.