Space junk falls back to Earth every day - from flakes of paint to bits of old rockets - but the threat of a falling bus-sized space station has garnered more interest around the world.
China's eight-tonne unmanned space lab Tiangong-1, or Heavenly Palace 1, is travelling at 7.7km per second and is predicted to re-enter the Earth's atmosphere sometime between Friday 30 March and Tuesday 4 April.
Tiangong-1 module blasts off in 2011. Source: AAP
Sound familiar?
Tiangong-1 was put into orbit in 2011, and after completing its five-year mission has since been on an uncontrolled orbit of the Earth.
If you think you've heard the name before, you have. Sandra Bullock's character in Gravity took a space ride on Tiangong — a futuristic version of Tiangong-1- which also happened to be hurtling towards our planet.
Sandra Bullock in the film Gravity. Source: Warner Bros. Pictures/AAP
Where will it crash?
It's difficult to calculate where parts of the spacecraft could crash into Earth, experts say.
The fuel tank is likely made of titanium, giving it a chance of making it back to Earth.
But given its speed and other factors, crash sites include everywhere between the latitude of 43 degrees north and south - spanning an area stretching from southern France to Hobart.
Should I be worried?
Chances it will land in a populated area are slim, let alone hit anyone.
"Anything is always possible but it's just highly unlikely that this one fuel tank that may or may not survive is going to slam into someone's house or into someone," Flinders University space archaeologist Alice Gorman told AAP.
Instead, Australians may be in for a "spectacular" night sky.
"The thing that would be really nice, if it re-enters over Australia at night, is that we'll get to see a spectacular sight of the spacecraft breaking up and lighting up as it comes in like a meteor shower," Dr Gorman said.
The temperature and density of different parts of the atmosphere, the Sun's activity, and what parts are facing Earth will all come into play.
But not knowing the components of Tiangong-1 makes estimating the danger more challenging, Swinburne University astronomer Alan Duffy said.
"China's secrecy around this nationally significant space mission has meant that the international community doesn't know what the craft is made of," Professor Duffy said.
Who is liable if it hits something or someone?
Even if it falls on Australian land, a United Nations agreement means any part of Tiangong-1 remains the property of China.
That also ensures China is liable for any damage.
Space lawyer Kim Ellis said it would mean the federal government could present a claim for damage to China should Tiangong-1 collide with and damage a satellite from Australia or damage people or property within Australia.
So watch this space.
- With AAP
