Update The European Space Agency was set to crash its Rosetta space probe into comet 67P/Churyumov-Gerasimenko as the final stage of its 12-year research mission at 12.18pm BST today (7:18am EDT).
The 19km descent from orbit was to end with a walking pace impact but Rosetta is not designed for landing and is not expected to survive. The comet is just over 719 million kilometres from Earth, and moving further away. Being 573 million kilometres from the Sun has also reduced the effectiveness of its solar panels.
Mission controllers considered putting the probe to sleep and trying to wake it up again when it got closer. But it was unclear whether this would work and a decision was made to go out with a bang.
It is hoped the probe could take images from as low as a few metres above the surface. At the time of writing, Rosetta is 5.8km from the surface and still taking pictures.
The ESA team tweeted some of its last commands here:
Rosetta flight director Andrea Accomazzo told the BBC: "We're now entering the final stage of the space segment of the mission, if you like. But Rosetta's data will be exploited for decades to come.”
Rosetta took 10 years to the reach the comet arriving in November 2014. Since then it has taken over 116,000 images of the comet, giving rare insight into its chemistry and structure.
In November 2014 it dropped a robot called Philae onto the comet’s surface.
There are various ways to follow the action here.
And – sorry about the Flash, not in our control – there’s a live video below or you can go directly to the page here. ®
Updated to add: The spacecraft has officially crashed, by which we mean the telemetry data has flickered out. We doubt it missed its target.