It is likely to impact the thicker parts of the atmosphere and burn up sometime late on Sunday, according to orbital tracking experts.
The Russian space agency says little of the probe will survive to the surface.
It calculates no more than 200kg in maybe 20-30 fragments.
Precisely where on the Earth's surface - and when - this material could impact is impossible to say, however. There are huge uncertainties in forecasting the final moments of a re-entry.
"The major uncertainty for prediction is the atmospheric density the spacecraft encounters in orbit, but it's also due to the orientation of the vehicle as it comes in," explained Prof Richard Crowther, the UK Space Agency's chief engineer.Continued