The Chinese Tiangong program, literally meaning "Celestial Palace", aims to develop a space station with general characteristics (mass and size) similar to those of the unforgettable Russian Mir. The first phase placed the Tiangong-1 module in orbit in September 2011. After five years, Chinese authorities confirmed that it will disintegrate in the atmosphere at the end of 2017. The problem is that this "reentry" will not be fully controlled.
A Mission That Went Silent
Nobody doubts that the Chinese space station Tiangong-1 fulfilled its mission within established parameters. It received a total of three visits during its first 24 months in orbit, through the missions Shenzhou 8, 9, and 10. The last two of these were crewed, notably including China's first female astronauts, Liu Yang and Wang Yaping. With Shenzhou 10 departing in June 2013, Tiangong-1 was placed in suspension, so the plan was for it to remain in orbit longer, transmitting data on its integrity. However, in March 2016 that link was interrupted, and since then, speculation has been that Chinese authorities lost control of the station. According to the Xinhua news agency, the director of the Manned Space Engineering Office, Wu Ping, confirmed that Tiangong-1 will fall to Earth in the "second half of 2017", and that "most of its parts" will disintegrate in the atmosphere.
Concerns About an Uncontrolled Reentry
That is exactly what bothers and worries experts. "Second half of 2017" and "most of its parts" cast a shadow of uncertainty over the module's fate. Tiangong-1 measures 10.4 meters long and has a mass exceeding 8,500 kilograms, so it is not possible to completely rule out that some fragment could cause damage on the surface. As astrophysicist and Chandra Observatory member Jonathan McDowell explains, not knowing precisely "when" it will fall means it won't be possible to know "where" it will fall, and a change in atmospheric conditions could move the debris "from one continent to another".
https://www.youtube.com/embed/6S8_1xBK398Although statistics are in the station's favor (most likely it will fall in the ocean or a desert) and Chinese authorities will continue monitoring its trajectory, nobody wants to see pieces of 80 to 100 kilograms over a residential area. Meanwhile, China has already begun the second phase of its Tiangong program, with the successful launch of Tiangong-2 (video above) on 15 September. The new module will receive two astronauts in October under the Shenzhou 11 mission, who could stay up to 30 days in space.
