The delay is the result of readings JAXA has received about the asteroid's surface. Apparently, Ryugu's surface is more rugged, and therefore more challenging, than was initially expected. "We had expected the surface would be smooth . . . but it seems there's no flat area," project manager Yuichi Tsuda explained. The team needs more time to figure out the best way to land the probe, which is about the size of a refrigerator, on the surface without hitting any rocks or damaging the craft.

Hayabusa2 already has smaller instruments aboard Ryugu's surface. MASCOT, a 22-lb robot, successfully landed last week and has been taking measurements, looking at surface minerals and more. And two tiny rovers, known as MINERVA-II, were dropped in early September, and are making their way across the asteroid's surface by jumping, thanks to Ryugu's low level of gravity.