Up until Shenzhou 8, the orbital module of the Shenzhou was equipped with its own propulsion, solar power, and control systems, allowing autonomous flight. It is possible for Shenzhou to leave an orbital module in orbit for redocking with a later spacecraft, a capability which Soyuz does not possess, since the only hatch between the orbital and reentry modules is a part of the reentry module, and orbital module is depressurized after separation. For future missions, the orbital module(s) could also be left behind on the planned Chinese project 921/2 space station as additional station modules.