China's first unmanned space laboratory, the Tiangong-1, lifted off from the Jiuquan Satellite Launch Center on September 29. Yang Hong, the chief designer of the module, talks about the challenges of staying in orbit and its significance to China's space program.

What are the key technologies used in Tiangong-1?

Yang Hong: We have made several breakthroughs. First, we have verified the various measurement equipments essential to successfuly redevous and docking. Second, when the two vehicles docked together, they form a complex.

How to control and manage the complex requires another technological innovation. Tiangong-1 is the first Chinese spacecraft to orbit the Low Earth Orbit. Staying in orbit for two years is another breakthrough. Mastering these technologies will pave the way for establishing China's own space station in the future.

Tiangong-1 is expected to carry out China's first space docking, what are the challenges?

Rendevous and docking is a sophisticated technology. It's also essential to building China's own space station. Two high speed vehicles orbit on the Low Earth Orbit, gradually close in, and form a connection when the active vehicle captures the passive vehicle. This procedure is done with vehicles orbiting at high velocity, so we employ various measurement technology to ensure that it be a safe and precise docking. By then, China will become the third country in the world, after United States and Russia, to master the rendevous and docking technology.

Tiangong-1 is likely to stay in orbit for two years, what difficulties will it face?

During its two-year lifespan, Tiangong-1 is likely to face a severe space environment. First, we make sure all the equipment and facilities are in good condition, the manned environment inside the pressurised module are safe. Second, a series of measures are taken to ward off the radiation, space debris and meteorite. Tiangong-1's space shielding plate is able to resist slight collision. Besides, the monitoring and early warning in Ground System will alert us potential threats. "

The astronauts are expected to work inside the module, once the manned docking is accomplished. What special facilities are onboard to help them adapt to the environment?

The astronauts are expected to work and live in micro-gravity environment.

The temperature, humidity, illumination and noise control should meet the medical requirements. And hazardous gases or trace contamination are monitored. Astronauts have supporting facilities to carry out experiments. Equipments such as bicycle ergometers and lower body negative pressure suits will help them maintain health. The astronauts could use personal computers, send messages, or start a two-way video communications with people on the ground, in return, the ground staff also upload emails to them.

What happens to Tiangong-1 after its mission in space?

We have left room for enough propellant in the designing phase of Tiangong. After its mission in the space, Tiangong-1 will deorbit, re-enter earth, and fall to the designated spot. No space trash will be left. We observe international rules. It's also our responsibility as a space-faring nation.

What's the significance of the Tiangong-1 mission?

Tiangong-1 will dock with Shenzhou spacecrafts and complete the second step of China's space program. But our ultimate goal is to build China's own space station. The docking technology is essential to assemble a multi-module structure. Tiangong's successful liftoff will be followed with a series of dockings.

(CNTV.cn September 29, 2011)