I thought that too, but then they wouldn't be able to target the first spot so perfectly if they haven't considered that. And assuming 12h day the rotation should be around 2 pi R / 12 h ~= 2 km /h assuming R=4 km.
That would result in much bigger velocity than 0.5 km/h when bouncing, and would exceed escape velocity 2 times, just from horizontal part of velocity).
