Some time within the next few months China's space laboratory will coming crashing down to Earth and no one knows where it's going to land.

China's first space laboratory, the Tiangong 1, was launched in September 2011 and was marked an important step forward for the country's expanding space program.

The lab served as a base for space experiments and hosted two three-person crews - including China's first female astronaut, Liu Yang, reports News.com.au.

Then in September last year, Chinese officials said they had lost control of the space lab and expected it to crash into Earth during the later months of 2017.

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China said the 10-metre long ship, which weighs 8500 kilograms, would burn up during its re-entry to Earth.

Officials told the United Nations it would closely monitor Tiangong 1's descent, but believed there was nothing to worry about.
But not everyone agrees.

Astrophysicist Jonathan McDowell said pieces weighing up to 100 kilograms could make it through the atmosphere and slam into Earth's surface.

He added changes in the atmosphere could result in the space junk slamming anywhere on the planet.

"You really can't steer these things," he told The Guardian. "Even a couple of days before it re-enters, we probably won't know better than six or seven hours, plus or minus, when it's going to come down.

"Not knowing when it's going to come down translates as not knowing where it's going to come down."

Uncontrolled crashes of spacecrafts are nothing new, with NASA's Skylab space crashing into Western Australia in 1979.

The Soviet Salyut 7 space station also plummeted Earth in 1991.

When controlled spacecrafts return to Earth, scientists guide them to the Oceanic Pole of Inaccessibility - a four kilometre deep area of the ocean located 5000 kilometres off the eastern coast of New Zealand.

Since 1971 more than 263 vessels have found a resting place in the "spacecraft cemetery".