Shenzhou 8 was launched on Monday and ground controllers commanded the spacecraft to catch up with Tiangong 1 - that was traveling at 5 miles per second - in five separate maneuvers. However, as the unmanned vehicle approached the prototype module, it kicked into fully-automatic mode, allowing its onboard sensors to guide the craft in. The final 30 miles before docking was automated.
As the two vehicles touched, a mechanism latched their hatches together, and ten minutes later, applause from mission control signified the two hatches had formed and airtight seal. The docked vehicles will remain attached for 12 days.
After the 12 days, Shenzhou 8 will undock, retreat about 140 meters and then re-dock with Tiangong 1. Should it be successful for the second time, this will prove that the first docking procedure wasn't a fluke.
Two days after the second docking, Shenzhou 8 will undock and begin reentry procedures. It will return to Earth, bringing a suite of biological experiments back to scientists waiting on the ground.