Both spacecraft were unmanned for the mission. The Shenzou craft was the active participant in the docking, firing its thrusters to nudge its way closer to the (relatively) stationary Tiangong-1. Guided by optical and radar sensors, the two glided to a secure lock between their docking rings, at which time twelve hooks locked the two spacecraft together. A dozen pins then made electrical connections between the two. The maneuver took place at roughly 211 miles altitude directly above China and required just ten minutes to complete.