The Shenzhou-8 will perform China’s first space docking mission with the Tiangong-1 space lab - otherwise known as Heavenly Palace. Successfully mastering the technology to carry out such a complex procedure is one of the key steps towards building large orbital platforms -- and flying missions beyond low earth orbit.

Space docking technology requires two vehicles to enter the same orbit and eventually -- and carefully -- come together. Any wrong moves or bad calculations could lead to disaster.

For any permanent base in space, the ability to dock is vital for the transport of crew, supplies and maintenance equipment.

The actual docking procedure is completed in four stages: Guided by a ground control center, the docking craft first adjusts its orbit several times until it’s under 100 kilometers away from the target vehicle.

At this point, the automatic docking systems on both vehicles kick in -- slowly bringing them closer together until they’re only a kilometer apart. The third stage is the final approach, and requires a very high level of accuracy.

The vehicle positions itself in alignment with the target vehicle, at a distance of only 100 meters. It then moves closer at a speed of 1 to 3 meters per second. Then, a small engine is fired to propel it towards the final docking position.

Finally, just before contact, the chasing vehicle shuts down its engine, to continue at the slow speed of just 15 centimeters per second -- until contact is made.

The locks are then applied, and wires and pipes connected -- to transfer power, communications data, and fluids. The two docked vehicles now orbit as one single combined spacecraft.

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