Before the space probe Hayabusa2 first touched down on the asteroid Ryugu, JAXA ran a series of touchdown rehearsals. In one, on October 14 and 15, 2018, the probe descended to about 22.3 meters above the surface to check the accuracy of its navigation and guidance. This test had been planned for an earlier rehearsal, but a sensor failed to switch modes.
In the next rehearsal, from October 23 to 25, the probe fed its laser range measurements back into its control. The first touchdown was postponed to January 2019 or later.