Tiangong Falls Out Of The Sky, China Must Ask Itself Why

Could the prospect of burning debris from Tiangong-1 raining down on Earth herald a new area of cooperation between space agencies?

AsianScientist (Oct. 6, 2016) – By Monica Grady – China launched the second vehicle in its Tiangong (meaning ‘heavenly palace’) program to construct a space station in early September. Despite the success of the launch, the announcement was overshadowed by the acknowledgement that the prototype module Tiangong-1—which was always due to be replaced—is out of control and will, almost certainly, crash back down to Earth in late 2017.

The Chinese Space Agency revealed its plans to build a space station in 2007, and since then has made great progress towards achieving its goal. Tiangong-1 was unmanned, but was involved in three separate docking events with the Shenzhou transport vessel. Shenzhou 9 and 10 carried the first (Liu Yang) and second (Wang Yaping) Chinese female astronauts.

Tiangong-1 operated for its full two-year lifespan. The original program suggested it would go through a planned de-orbiting prior to controlled Earth re-entry. The operation was extended for a further two years. There were no additional trips to the spaceship, and no news of what the purpose of its extended lifetime was—apart from a test of the space worthiness of components.

In March 2016, the Chinese Space Agency announced that Tiangong-1 had come to the end of its life, and also revealed that they had lost communication links with the satellite. In mid-September, the Chinese Manned Space Engineering (CMSE) Office confirmed that they were no longer able to control the satellite’s orbit.


Calculating the risks

The announcement from CMSE came as no surprise to those working with satellites: all spacecraft in orbit around Earth are tracked, both by government agencies and enthusiasts among the public. It has been clear since the beginning of the year that Tiangong-1 was not following its planned trajectory—and calculations now predict that it will fall to Earth in 2017. Although de-orbiting of the spacecraft will not be controlled, according to CMSE most of it will burn up in the Earth’s atmosphere, and there is little chance of flaming debris falling on populated areas.

This reassurance has not been accepted without comment. It is predicted that debris will land anywhere between 43° north and 43° north south of the equator, a large swathe of the globe in which almost 90 percent of human population resides. The odds of a specific person being hit are very low, but the chance of someone being hit are relatively high, about 1 in 3,200. Eight tonnes of burning metal will certainly also be observable in the sky—and plenty of observers will track the spacecraft, even if its final entry point will not be known until entry occurs.

That said, we have survived far greater objects crashing to Earth in the past. The 150-tonne MIR space station burnt up in 2001 over the Pacific Ocean. This didn’t harm anyone but resulted only in a few fragments falling down. Similarly, the 77-tonne Skylab re-entered 1979 over the Indian Ocean without causing any damage.


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