Jay Melosh, a professor of Earth, atmospheric and planetary sciences at Purdue University in the US state of Indiana, assumes that debris fall on Earth’s surface at all the time, and with a spacecraft like Tiangong-1, most of its body would burn down high in the atmosphere, while denser parts are expected to fall to the surface of the planet.
Tiangong-1, launched from China’s main launch station at 43 degrees north, was the first space lab of the overall Tiangong program, which is slated to operate in space until 2023.
RT @esaoperations: #Tiangong1 reentry forecast: The current estimated window is ~24 March to ~19 April; this is highly variable. Access latest update from ESA's Space Debris Office https://t.co/TLpKod0fs7 pic.twitter.com/i7Body7zxB— ruimtevaart (@ruimtevaart) 23 февраля 2018 г.
Tiangong-1 was intended to be deorbited in 2013, but it did not come down then. In the years that followed, the China National Space Administration reported on having lost contact with the laboratory.
Swaying like a pendulum in the vacuum of space, the station is expected to come down anywhere between the central US states and the southern tip of Australia, though it will more likely happen at either of the two extremes.
Researchers say the event would come as a bit of surprise since it is impossible to know when and where exactly Tiangong-1 is coming down until a few days before the event. They added that even a few hours of uncertainty "span a lot of territory."
"That could be the difference between landing in Chile and the middle of the Pacific," Melosh remarked.
The Chinese satellite's story resembles that of the 1970's-era American space station Skylab, which crashed into the Indian Ocean and the lands of Western Australia in 1979. Although there was no real preparation for the fall due to the incredible uncertainty around it, there were fortunately no casualties.