China's upcoming Chang'e-3 Moon mission is a major step in their rapidly advancing space program. A four-legged lander will touch down and release a six-wheeled rover onto the Moon in December. That's a fairly advanced mission for a first landing, but it's also a test for greater things to come.

There's a lot of interest in the robot rover that will be carried on the mission, and that's understandable. The rover will return plenty of images and data. The rover deserves all the attention it receives, but we shouldn't forget the spacecraft that will deliver it to its destination.

The Chinese robot lunar lander doesn't look as interesting as the rover, but it's probably the most important part of the mission. Without a successful lander, there can be no rover tracks on the Moon and no mission at all. The lander must fly through deep space and orbit the Moon. It must descend from this orbit to a targeted landing.

It must hover above the Moon and take photographs. It must then land safely on the surface. Once it's down, the lander must safely deploy ramps and release the rover from its stowed position.

But its mission isn't over then. The rover carries a telescope and radio instruments that will turn it from a transporter into a lunar observatory. Some of these observations will be performed in concert with instruments on the rover itself.

So let's not forget that there are really two spacecraft at work on this flight.

China will probably launch a second rover later in this decade, and the landing stage used on the Chang'e-3 mission will get its second trip to the Moon. That will probably mark the last use of this rover design, but the Chinese lunar lander will still be on active duty.

The lander has been designed to serve as a multipurpose spacecraft. It's like a small flatbed truck that can carry whatever is placed on it to the surface of the Moon. China already has plans to use this lander to carry other items.

The next big item to fly atop the lander will be a small rocket stage, which will be used to return samples of lunar rock to Earth. This mission will also involve the use of a small tugboat spacecraft in lunar orbit, which will dock with the sample return carrier after it blasts off.

Planning for this mission still seems to be ongoing, but China will probably still use its "Moon truck" to land on the surface. Two sample-return missions are expected to fly.

We can expect this stubby but practical lander to fly at least four times, with two rovers and two sample-return missions. This analyst suspects that this will not be the end of the story. If the landing stage works well, China will probably want to use it for even more missions.

There could easily be more robot rovers, probably larger and more advanced that the current first-generation design. These will carry more instruments and last longer. Another mission could involve a static payload that does not leave the landing stage.

One obvious choice would be a large astronomical telescope. This could be an optical telescope that could evolve from the small ultraviolet telescope carried by the first lander. Alternatively, a radio or microwave dish could be unfolded on top of the lander, just as some satellites unfurl large antennas in orbit.

Ultimately, this lander could serve as the father of a new landing stage with a greater capacity and more sophistication. The payload it carries to the moon will be much heavier and complex. It will be a pressurized cabin containing Chinese astronauts.

Dr Morris Jones is an Australian space analyst who has written for spacedaily.com since 1999. Email morrisjonesNOSPAMhotmail.com. Replace NOSPAM with @ to send email. Dr Jones will answer media inquiries.