A European satellite will fall to earth sometime in the next few days, but scientists don't know where, The New York Times reported.
Satellites may seem small in space, but the one expected to drop weighs one ton. It will fall in 25 to 45 pieces, with the largest unit possibly weighing up to 200 pounds, according to The Times.
"It's rather hard to predict where the spacecraft will re-enter and impact," said Dr. Rune Floberghagen, the mission manager for the European Space Agency's falling satellite. "Concretely our best engineering prediction is now for a re-entry on Sunday, with a possibility for it slipping into early Monday."
The satellite in question, named the Gravity Field and Steady-State Ocean Circulation Explorer, or GOCE, ran out of fuel last month and has been falling at a rate of 2.5 miles per day.
No one has ever been hit or injured from falling space equipment scientists refer to as "uncontrolled entries" nor is the occurrence that rare. Approximately 100 tons of aeronautical debris is expected to fall from the sky by the end of this year, according to The Times.
Still, the machinery has the potential to do damage, especially ones of GOCE's size. In two similar events, one involving NASA's decommissioned Upper Atmosphere Research Satellite from two years ago, both satellites fell harmlessly in the Pacific Ocean, The Times reported.
According to Dr. Floberghagen, the largest piece of debris will cover around 15 to 20 square yard, which "if you compare that to the surface of the planet, it's a very small number," he said.
GOCE was actually intended for "uncontrolled re-entry" when it was first made in 2009. It was also designed to orbit closer than most satellites to compile more accurate measurements of ocean currents, The Times reported.
"We can actually map, see geology, in the gravity map," Dr. Floberghagen said. "This is something that is quite unique, actually."
Now that it's served its purpose, GOCE will descend like an airplane out of gas.
"Quite literally GOCE is now nearly flying like an airplane without an engine, with the upper layer of the atmosphere providing aerodynamic stabilization," Dr. Floberghagen said.
As the satellite gets closer to earth, scientists will have a better idea of when and where it will land, according to The Times. It could be one of the last major episodes of uncontrolled entry after new regulations were made by the United Nations in 2008 (just after GOCE was designed).