"Even a couple of days before it re-enters we probably won't know better than six or seven hours, plus or minus, when it's going to come down," Harvard astrophysicist Jonathan McDowell told The Guardian in 2016. "Not knowing when it's going to come down translates as not knowing where its going to come down."
While much of the spacecraft would likely burn up in the atmosphere, ESA experts say portions could survive and reach Earth's surface.
"The date, time and geographic footprint of the reentry can only be predicted with large uncertainties. Even shortly before reentry, only a very large time and geographical window can be estimated," said Holger Krag, head of ESA's Space Debris Office.