Using Lunar orbit rendezvous (LOR) greatly increases the mass returned to Earth, a few hundred grams for the Russian Luna sample return missions compared to two kg for LOR. This is because you do not need to carry the 1 km/s of return propellant from Lunar orbit all the way down and back up again (a 4 km/s penalty).Using Lunar orbit for the return also allows return from any point on the Moon. If using a single burn direct ascent like the Luna missions, you are restricted to certain areas of the Moon, I believe to be in the Eastern hemisphere.
I thought, that doing lunar orbit automatic docking in sample return missions could mean also technology test, which can be greatly needed for manned missions. Don't know exactly why , but for me may be useful for precise testing of spacecraft and landing before actual human flight, or for orbital maneuvers without human presence like for constructing orbital station.
Docking tests with crews can be done in LEO, which is why I linked this approach to possibly technology-testing for a Mars mission.But I still don't see why they would want to complicate and already-complex mission which only the Soviet Union has previously accomplished.
I have just been reviewing all of the animations of the Chang'e 3 mssion which I can find online - mainly at YouTube - and all of these depict a direct return from the lunar surface, like the Luna sample-return missions.So, was the Chinese article wrong in what it said about a rendezvous in selenocentric orbit or have the Chinese decided the re-design and complicate the mission profile in the last three years or so?
Since the Chinese originally announced Chang'e-1, Chang'e-2 and Chang'e-3 as being the lunar orbit, lunar landing/rover and sample return missions respectively, there is plenty of room for confusion since Chang'e 3 will be the first rover mission!Maybe we should think of the original designators as being Phase 1, Phase 2 and Phase 3 respectively, with the flown Chang'e 1 and 2 being the Phase 1 missions and Chang'e 3 (and Chang'e 4? - even Chang'e 5??) being Phase 2 missions.