The Shenzhou spacecraft has a service module,a re-entry module and an orbital module and weighs 7.8 tonnes.
There also is a launch escape system on the top.
I'm wondering: why not have placed the orbital module underneath the spacecraft, separate from the service and re-entry modules?
Once in orbit (the launch escape system would have had a smaller mass to eject), the spacecraft would have turned around and docked with the orbital module (like Apollo ASTP did with the airlock module).
The orbital module's solution is a way to reduce the re-entry module to an absolute minimum mass so that a parachute and last second rocket exhaust can allow it to land on the land. The orbital module carries everything that's essential for an operational mission in space.
With a separate orbital module, it's possible to change its purpose according to the flight, but it would also make it possible to slightly change the re-entry module (to carry more crew).
Just a guess.

Raoul