A one-tonne satellite is set to smash into Earth on Sunday - but scientists have no idea where.
The Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) will reenter the atmosphere between 6pm and midnight.
Although much is expected to burn up, but up to a quarter will survive and hit the ground.
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The European Space Agency (ESA) insists the risk to humans is incredibly low and have ruled out it landing in Europe.
Professor Heiner Klinkrad from the ESA said: "At present we can not say where the re-entry is going to happen except that it is not going to happen north of the 85 northern latitude or south of 85 southern latitude.
Klinkard pointed out that around 15,000 tons of space debris has fallen to Earth since the launch of Sputnik, the very first satellite.
He added: "Most of this burns up when it re-enters in the atmosphere due to aerothermal heating.
"So typically between 10% and 40% of the initial mass survives such a re-entry. And the few pieces that survive than reach the ground, but with much reduced velocity."
GOCE was launched in 2009 to map variations in Earth’s gravity and has functioned for three times as long as intended.
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