Chinese space station Tiangong-1 to fall to Earth within next few days

In a few days, the Chinese space station Tiangong-1 will fall out of orbit, burning up in Earth's atmosphere, but space authorities still don't know exactly where.

Tiangong-1 was China's first space station, launched in 2011, and visited just twice by Chinese astronauts. In 2016, the Chinese space agency announced it was no longer tracking the 12-metre by 3.3-metre eight-tonne station.

China says it has lost control of the station and there is no way to know where it will re-enter the atmosphere.

Most of the space station will likely burn up during re-entry, but there's a slight chance that pieces of it may reach the ground.

Below you can watch a simulation of the re-entry by the Aerospace Corporation, which is tracking the station.

Spacecraft around Earth need periodic adjustment to their orbits as a result of our planet's atmospheric drag. Tiangong-1 is unable to make those adjustments. The denser the atmosphere, the more drag it causes, which pulls the space station toward Earth. 

Space weather and the orientation of the spacecraft create uncertainty about the timing of Tiangong-1's re-entry. Solar flares or the speed of the solar wind can affect the atmospheric density.

Space debris common

There's no reason to be alarmed, however. Since the space age began in 1951, no one has been injured by a piece of space debris.

One woman, Lottie Williams, was hit harmlessly by a small piece of space junk as she was walking through a park in Tulsa, Okla., in 1997. She is the only person believed to have been hit by such debris.

Don't be afraid of the risk to you as a person. It's ridiculously low.- Stjin Lemmens, European Space Agency

Stjin Lemmens of the European Space Agency's Space Debris Office said as of March 27 it is predicting that Tiangong-1 will re-enter Earth's atmosphere between March 31 and April 2, somewhere between 43 degrees north latitude and 43 degrees south. That leaves most of Canada out, with just part of southern Ontario within the predicted area.

"Don't be afraid of the risk to you as a person," Lemmens told CBC News. "It's ridiculously low."

Space debris is fairly common, he said.

"This is by no means the first time this has happened," he said. "Over the past, well, nearly 60 years of space flight, we've had about 6,500 uncontrolled re-entries of satellites and rocket bodies."

This could include small satellites, spent rocket stages and, yes, even space stations.

In 1979, the 77-tonne U.S. space station Skylab fell toward Earth, with some pieces, both large and small, reaching the ground. The most famous was part of an oxygen tank that landed in Australia's outback.

One of the most recent re-entries of space junk, comparable to Tiangong-1 in size, occurred in 2015, when Russia's Progress cargo ship failed to reach a stable orbit. It re-entered the atmosphere uncontrolled and burned up over the Pacific Ocean. Some larger pieces are believed to have reached the surface.

As for whether you might catch a glimpse of the station breaking up — which can be quite spectacular — it all depends on a few factors including location, time of day and cloud cover.