You might want to keep your eyes on the sky over the next few months.
A Chinese space lab, called Tiangong-1, is currently hurtling towards Earth and is expected to re-enter into our atmosphere sometime between now and early next year.
Yep. It sounds like something straight out of a sci-fi film … and in a way it is.
Remember that space station Sandra Bullock hitched a ride on in Gravity?
That was Tiangong — a futuristic version of Tiangong-1 — and coincidently it also was hurting towards Earth at the time.
But back to what’s actually happening.
Tiangong-1 — or “heavenly palace” — was originally launched by China’s National Space Administration back in 2011.
The 12-metre lab, which weighs about 8.5 tonnes, was a major step towards the country’s goal of building a space station by 2020.
It was also where China’s first female astronaut, Liu Yang, flew on a mission in 2012.
But things went wrong when China lost control of the lab last year, and now they are playing a waiting game, trying to anticipate when and where it will fall to Earth.
Space archaeology expert Alice Gorman, from Flinders University, said while China will be able to monitor its descent, it won’t be able to control its landing.
“Contact has been lost with the spacecraft, so apart from monitoring its position the re-entry is uncontrolled,” she said.
So where is it now?
In September 2016, China’s Xinhua news agency reported that Tiangong-1 was “intact and orbiting at an average height of 370 kilometres”.
Since then it has dropped about 60 kilometres, Dr Gorman said.
What will happen when it enters Earth’s atmosphere?
Dr Gorman said Tiangong-1 is travelling at high speed — estimated at about 27,000 kilometres per hour — and will burn up when it re-enters Earth’s atmosphere.
Orbits and what you’ll find there
- Low Earth Orbit: Remote sensing satellites are commonly found here orbiting at about 500 to 600 kilometres above the ground.
- Medium Earth orbit: Typically you’ll find GPS satellites here orbiting around 20,000 kilometres above the ground.
- Geostationary (‘Geo’) Orbit: Home to communication satellites, orbiting 35,000 kilometres up.
“When it hits the atmosphere it will start to slow down and heat up, due to friction and atmospheric compression. As it heats, it will break up into burning fragments,” she said.
Will we be able to see it from the ground?
“Depending on what time of day and the geographic region, it could provide a bit of a fireworks display for people on Earth,” Dr Gorman said.
Should we watch out for bits of steel falling from the sky?
Dr Gorman said its likely that some bits of Tiangong-1 will survive re-entry.
“Usually these are materials with the highest melting temperature and the most insulation,” she said.
“Generally titanium pressure vessels and stainless steel fuel tanks are the most common spacecraft component to survive re-entry.”
Dr Gorman said Tiangong-1 had steel alloy tanks, but an analysis of the materials suggested they would burn up long before they reached the ground.
“People don’t need to be worried about being hit,” she said.
Has this happened before?
Yes. It’s a rare event, but a number of other large spacecraft have made the fiery journey back to Earth.
“This has happened with the USSR Salyut series — there were seven of them — and the Mir space station in 2001,” Dr Gorman said.
“Most famously, the US space station Skylab fell back to Earth over Western Australia in 1979.
“In some parts of the world, this caused a lot of uncertainty and fear, but West Australians all went outside to watch the spectacle by all accounts.
“The story about how the the Shire of Esperance issued a littering fine to the US State Department is well known — this fine was later paid by a radio station fundraising in 2009.”