Special Missions

As the China Manned Space Engineering Office (CMSEO) briefed, Tiangong-1 is the first component of China’s space station and a simply equipped experimental space laboratory. “Tiangong-1 is a new type of manned spacecraft,” said Deputy Commander of CMSEO Niu Hongguang. “To date, it has the longest lifespan of all Chinese spacecrafts in low Earth orbit. It is the prototype of China’s first space lab.”

Launching an unmanned laboratory is usually the first step on the way to setting up a space station where astronauts can carry out scientific experiments. After precise tests of Tiangong-1’s safety are made using a reliable database, the next step will be to send up a manned spaceship that will be connected to the laboratory using rendezvous and docking technology so that the astronauts will be able to enter the laboratory to work. On completion of their missions, the spacecraft will then undock from Tiantong-1 and the astronauts will return to earth.

This will be the first of three spacecrafts that will dock with Tiangong-1 over the next two years, testing the rendezvous and docking technologies, technical hurdles that must be cleared in order for China to successfully build a space station.

In the docking process, Tiangong-1 will be a target spacecraft with a passive docking port. It will wait for the visiting spacecraft to enter low Earth orbit, sending out signals to indicate its location. The visiting spacecraft will slowly approach Tiangong-1, and, as the active vehicle in the process, will form a connection after it captures the lab. Tiangong-1 will then take control of the active vehicle’s fuel, information systems, thermal environment, movement and orbit.

Tiangong-1 will be where the astronauts work and live. Deputy chief designer of the astronauts system, Wang Xianmin, commented that though Tiangong-1 is currently unmanned, systems necessary for manned spacecraft, such as moderated environment and life-support, have already been installed. It also carries equipment for the planned experiments in areas such as remote sensing and materials science in space, and for technical preparations for the future space station.

Remote sensing exploration using high-resolution hyperspectral imaging will be used in multiple areas, including resource exploration, environmental monitoring, and even food safety issues. “These experiments will bring about tangible benefits for the common people,” explained Zhang Shancong, deputy chief designer of the Space Application System. “It can detect pollutants in the air, heavy metals in crops, and even oil and gas reserves. This technology has been widely applied for civil use.” As for research into materials science in space, the microgravity in outer space provides ideal conditions for research into new materials and their potential uses.

Technical Advantages

Wu Ping, spokeswoman of the China Manned Space Engineering Project, said, “Different from the early strategies applied in the rendezvous and docking tests of the U.S. and the Soviet Union, we’ve designed Tiangong-1, which has more technical and economic advantages. First, it can dock several times, reducing the number of launches. Second, it is designed to carry out the crucial technical tests and pave the way for the future space station. Third, the scientific experiments and technical tests can be carried out simultaneously.”

At high velocity, precision is crucial to avoid collisions during rendezvous and docking. There are more than 500 devices on Tiangong-1 to assist in-orbit operations and proper functioning. Furthermore, during its two-year lifespan, it faces all types of possible risks, including those posed by space junk and solar storms. Chief Designer of China’s Manned Space Program Zhou Jianping remarked that, throughout the processes of design, analysis, simulation, experiments and tests, many possibilities have been considered in order to secure the safety and precision of Tiangong-1 during its two years of service and hundreds of plans are ready to deal with possible faults that may occur.

It is said that the number of space debris more than one centimeter in diameter exceeds 110,000, ranging from satellite fragments, coating fragments, and dust to completely intact rocket engines. These have the potential to be fatal to Tiangong-1 at the speed of thousands or even tens of thousand meters per second that the module will be traveling at. Tiangong-1’s two-to-three-mm metal covering and specially designed protective devices will protect it from minor debris, while it will avoid bulkier objects using an emergency mechanism receiving signals from Earth to temporarily alter its flight path and speed.

Solar storms, made up of streams of charged particles given off by the sun, which have been colorfully referred to by scientists as the “sun’s sneeze,” are another threat to the precision of rendezvous and docking, as they can alter the speed of orbiting satellites. To avoid such problems, Chinese scientists produced a solar photospheric and chromospheric telescope in 2008 and a solar radio telescope this year to predict solar storms.