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China’s space lab could crash to Earth on Saturday, scientists say


But chances of being hit by a piece of debris are smaller than winning the lottery, experts predict


One of the largest Chinese spacecrafts in orbit could crash back down to Earth as early as Saturday, authorities said on Monday.


The re-entry of Tiangong-1 into the atmosphere “will be between March 31 and April 4, 2018,” according to a statement posted on the website of the China Manned Space Engineering Office.


While most components of the eight-tonne craft are expected to burn up as it re-enters the atmosphere, some debris might survive and make it back to ground level, the statement said.


Beijing has been unable to pinpoint where the debris might fall because the spacecraft is now entirely out of control. It has been tumbling and spinning randomly, so scientists have been unable to map its trajectory.


Some experts have said Tiangong could crash anywhere between 43 degrees north latitude and 43 degrees south, a massive area that would include parts of the United States in the north, to Australia in the south.


Dr Zhu Jin, director of Beijing Planetarium, said, however, that the chances of anyone being hit by a piece of falling debris were lower than those of winning the lottery.


The most likely outcome was that any pieces of the spacecraft that did make it through the atmosphere would land in the sea, which covered 70 per cent of the Earth’s surface, he said.


The Aerospace Corporation put the odds of someone being hit at less than one in a trillion.


People should just sit back and enjoy the spectacle, as if it were a really expensive firework, Zhu said. The 10-metre long spacecraft cost hundreds of millions of yuan to build.


“When it enters in the atmosphere, it may look like an unusually bright, unusually slow meteorite,” he said.


But even witnessing the event would require luck, as the re-entry might not even be visible if it happened during the day, Zhu said.


Tiangong-1 was orbiting at an average altitude of about 212km on Monday, or about 4km lower than the day before, according to China’s manned space programme office.


The estimated crash date is based on analysis performed by the Beijing Aerospace Flight Control Center and other professional organisations, according to the official statement.


The European Space Agency made a similar forecast over the weekend, setting the date at between March 30 and April 2, “give or take a few days”.
The Chinese government said it would release monitoring information and upxed forecasts on a daily basis.


Tiangong-1 was put into orbit on September 29, 2011 as a stepping stone towards the launch of China’s first full-size space station, which is expected to be completed in the early 2020s.


The laboratory comprised several modules and was able to support up to three astronauts for two weeks at a time. In its lifetime it was involved in six rendezvous and docking missions with manned Shenzhou spacecraft, and made “significant contributions to the development of China’s manned space mission” space authorities said.


On March 16, 2016, Tiangong-1 terminated its data service, officially ending the mission and starting its orbital decay.
Tiangong-2, a similar spacecraft, remains in orbit and is functioning as it should.


Nasa’s 85-tonne Skylab space station is the largest spacecraft ever to make an uncontrolled return to Earth. Several large pieces of debris from it crashed into the Australian town of Esperance in 1979.
The town’s authorities issued Nasa with a US$400 fine for littering, but the US space agency never paid up.

美国宇航局发射的85吨重天空实验室空间站是有史以来最大的返回式航天器。1979年,其坠落后产生的几块大碎片坠入了澳大利亚Esperance 镇。