A crippled Russian spacecraft is likely to crash to Earth sometime on Sunday at an unspecified location.
But experts say the impact poses little danger because the spacecraft's 11 tonnes of toxic rocket fuel is likely to burn up as it passes through the upper atmosphere.
The aluminium fuel tanks of the Phobos-Ground probe will heat up and melt at the temperatures experienced by the spacecraft as it hurtles back to Earth. This will ensure that the fuel is either burned up or dispersed, Professor Richard Crowther, chief engineer of the UK Space Agency, said.
The spacecraft, which failed to be fired out of its low-Earth orbit after a problematic launch in November from the Baikonur cosmodrome in Kazakhstan, was designed to land on Phobos, one of the two Martian moons. But it is now destined to break apart somewhere between 51.4 degrees north – encompassing southern England – and 51.4 degrees south.
Professor Crowther said it is unlikely that the Russian space authorities have retained any control over Phobos-Ground, which is about the size of a mini-bus and weighs 13 tonnes.