China's first space laboratory is still in orbit and still working. The Tiangong 1 spacecraft is observing the Earth and measuring the space environment more than two and a half years after its launch. It isn't clear when the mission of this robust module will end, but we can be sure that it will never host any more visiting astronauts. Tiangong 1's flight is not over, but it's high time for China to tell us more about its successor, Tiangong 2.

China is expected to launch its second space laboratory at some point in 2015. Like its predecessor, Tiangong 2 will be a small pressurized space station that will house astronauts launched to it aboard Shenzhou spacecraft. Tiangong 2 could be China's last "space laboratory" before work begins on the "Chinese Space Station", a large modular structure expected to be launched around 2020.

Tiangong 1 was an outstanding success and we know a lot about it, thanks to ample coverage in the Chinese media. Similarly, we know a fair amount about the upcoming Chinese Space Station, from graphics and stories released by China. Yet the next big project for China's human spaceflight program is still an enigma, like some strange form of "missing link" in the evolution of Chinese spacecraft.

This is not the first time that this analyst has written about the confusion surrounding Tiangong 2, but the subject is too important to be ignored. Furthermore, China's ongoing "code of silence" surrounding this spacecraft could actually be telling us things.

One point that could be raised is that this is further evidence of a general clampdown on media discussion of sensitive subjects, space or otherwise. This analyst has previously noted that the first crew expedition launched to Tiangong 1 in 2012 was covered very well by Chinese media. By 2013, when the next crew was launched, the coverage had dropped substantially.

This couldn't entirely be explained away by suggesting that the second flight was less historically significant than the first. It seemed that a new policy of censorship was in place. There was a plausible explanation for this. In between these missions, Xi Jinping assumed the Presidency of China. It has since been documented that China is experiencing revisions to its use of conventional media as well as social media. Our experiences with Tiangong 1 were one of the earliest demonstrations of this policy shift.

There is also the possibility that the Chinese themselves have not fully settled on their plans for Tiangong 2. Technical problems with anything from the Tiangong spacecraft to the rocket intended to launch it could be behind this. One easy option could be to launch a similar module to the relatively small Tiangong 1 spacecraft on a Long March 2F/G rocket, the same rocket used to launch Tiangong 1.

But analysts have suspected that China is really planning a larger, more complex module with multiple docking ports. This would be too heavy for the Long March 2F/G, and would probably require one of the new rockets under development by China, such as the Long March 7. Right now, this rocket has yet to be flight tested. The Chinese could also be considering a more ambitious mission with the Long March 5 rocket, which is even more powerful than Long March 7. It has also yet to make its debut.

So China could be weighing up the options: Play it safe by using proven technologies, or deploy something new and riskier. In practice, China probably has little to gain by simply repeating the Tiangong 1 mission sequences. Thus, the odds are probably still in favour of a new type of module, even though it poses challenges. China has also suggested that a cargo vehicle will be docked to Tiangong 2, and some type of refueling experiment could also take place. This would seem difficult to perform with a basic Tiangong module.

A preliminary review of the conference papers China plans to present at the International Astronautical Congress later this year suggests that there will be no specific presentations on Tiangong 2. That's disappointing, but it also reinforces the aforementioned observations on the "code of silence". The closer we get to the expected launch phase for Tiangong 2, the cagier China seems to get.

At some point, China has to place its cards on the table. We will be getting closer to the expected launch window. China will then need to say if the launch has been delayed or not. The expected test flights of the Long March 7 rocket will also hopefully trigger some more discussion. A successful debut of Long March 7 will boost confidence that it will be ready to support a heavy Tiangong module. Even by saying nothing, China still gives us clues to what's happening behind closed doors.

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.