The spacecraft is expected to crash at about 11.40am on Friday, Irish time
Final plans are being made for the crashing of a European spacecraft on to a comet, a sad but necessary end to the €1.4bn Rosetta mission.
The spacecraft is set for a one-way trip to the bleak and rugged surface of comet 67P/Churyumov-Gerasimenko, where it is expected to crash at about 11.40am on Friday, Irish time.
Rosetta was not designed to land and so will not survive the crash, with confirmation of the sad ending expected at around 12.20am Saturday - the delay is because Rosetta's radio signals take a long time to reach Earth.
It will remain on the comet - a chunk of ice and dust measuring 2.8 miles across, as it continually travels around the solar system, something it could do for millions of years.
Churyumov-Gerasimenko circles the Sun between the orbits of Jupiter and Earth and Rosetta travelled for more than 3.9 billion miles to finally reach it in August 2014, having built up speed from four planetary flybys in a trip that took 10 years.
Once Rosetta was in position, the small lander Philae was deployed and travelled 14 miles to land on the 4km-wide lump of ice and dust as it hurtled through space.
But Philae bounced from its landing area and became lost, managing to transmit data for just three days before its battery died and it went into hibernation. It recharged enough to communicate briefly again in mid-2015.
The ESA has since switched off Rosetta's radio link with Philae but it is the lander's path which Rosetta will follow on Friday as she heads to her end.
The reason Rosetta has to be disposed of is that, as it heads further away from the Sun, its solar panels struggle to generate enough power for it to keep running.
Scientists will be watching the crash closely, hoping to recover Rosetta's final images before the the smash.
The European Space Agency's Rosetta flight director Andrea Accomazzo said: "For sure, Rosetta will bounce or tumble on the surface of the comet but will not bounce back into orbit.
"We could have abandoned the spacecraft but this is not what we want to do."