The European Space Agency (ESA) has said debris from a defunct European satellite re-entering the atmosphere will crash to Earth late Sunday or early Monday.
Parts of the large science satellite, called Europe's Gravity field and steady-state Ocean Circulation Explorer (GOCE),was just 160km above earth, operations manager Christoph Steiger wrote in a status report posted on the agency's website.
"Re-entry into the atmosphere (is) probably less than two days away," Steiger said.
The 1.2 tonne (1,200 kg) satellite was launched in 2009 to map variations in Earth's gravity. Scientists assemble the data into the first detailed global maps of the boundary between the planet's crust and mantle, among other projects.
GOCE ran out of fuel on October 21 and has been steadily losing altitude since, tugged by Earth's gravity.
Most of the spacecraft will burn up as it blasts through the atmosphere, but up to 50 fragments - or roughly 25 percent of the satellite - is expected to survive re-entry and end up somewhere on the planet's surface.
With two-thirds of Earth covered by water and vast areas of sparsely populated land, the risk to human life and property is considered extremely low, the European Space Agency said.
ESA said, on Friday, that humans are 250,000 times more likely to win the lottery than to get hit by the debris.
Yet, Italian officials warned there was a "minimal" risk that debris could hit Italy late Sunday or early Monday.
"It is not yet possible to exclude the possibility, even minimal, that one or several fragments could fall on Italy in two windows of time," the Civil Protection agency said in a statement.
It said debris from the satellite "potentially" could hit between 1844 and 1924 GMT Sunday and between 0648 and 0728 GMT Monday.
The regions at risk late on Sunday were in northwestern Italy and the central Mediterranean island of Sardinia.
The last big satellite to fall back through the atmosphere was Russia's failed Phobos-Grunt Mars probe. The 14 tonne spacecraft re-entered in January 2012.