New predictions for the defunct Chinese space station Tiangong-1 suggest it may fall back to Earth in mid to late March – but a Chinese engineer has quashed concerns that the re-entry is uncontrolled.
Tiangong-1 is currently orbiting about 270 kilometers (170 miles) above the surface of Earth. Launched in 2011, the station has been uncrewed since 2013 and, it’s believed, out of control. Its orbit is slowly degrading due to atmospheric drag, with most predictions suggesting it will have re-entered by April.
The exact date and location of re-entry are still not clear, but as the date approaches, we can improve our estimations. Last week The Aerospace Corporation pushed the date back from late February/early March to mid to late March.
With a mass of 8,500 kilograms (18,700 pounds), it’s thought that some of the satellite may make it to the surface of Earth (note, this is by no means the largest man-made object to return to Earth). Its orbital period takes it as far north as New York, and as far south as New Zealand.
“There is a chance that a small amount of Tiangong-1 debris may survive reentry and impact the ground,” Aerospace said, noting however that “the probability that a specific person (i.e., you) will be struck by Tiangong-1 debris is about 1 million times smaller than the odds of winning the Powerball jackpot.”
Nonetheless, the apparently uncontrolled re-entry has been cause for some concern. But last week an engineer at the China Aerospace Science and Technology Corporation (CASTC) said Tiangong-1 was not out of control at all, and it was being returned for a controlled splashdown in the Pacific Ocean.
“We have been continuously monitoring Tiangong-1 and expect to allow it to fall within the first half of this year,” the engineer, Zhu Congpeng, told the Chinese state-backed Science and Technology Daily newspaper.
“It will burn up on entering the atmosphere and the remaining wreckage will fall into a designated area of the sea, without endangering the surface.”
The paper went on to claim that the re-entry had been planned for September 2017, but it was purposefully delayed to ensure the wreckage fell into the South Pacific Ocean.
The Aerospace Corporation, for its part, has previously said it is unlikely this event is being controlled. “Although not declared officially, it is suspected that control of Tiangong-1 was lost and will not be regained before re-entry.”
And the European Space Agency (ESA), too, thinks this is likely an uncontrolled re-entry. “In so far as can be fully confirmed, ground teams lost control with the craft, and it can no longer be commanded to fire its engines,” they said. “It is, therefore, expected to make an ‘uncontrolled re-entry’.”
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