Rosetta in the UK

Rosetta’s mission to comet 67P/Churyumov-Gerasimanko is coming to an end – plans are already in place for a grand finale on September 30, when the orbiter will land gracefully (erm, crash) on the surface of the target it has been following so closely for more than two years. In preparation for the landing, Rosetta has been approaching ever closer to the surface. High resolution images of the surface have been returned, showing in great detail the stark and pitted landscape, ragged cliffs and boulder-strewn plains.

How do you say goodbye to a valued colleague with whom you have worked closely for almost two decades? Maybe there is a farewell party, a collection for a gift, a bunch of flowers? If the colleague is moving to an exciting new post, the affair is usually joyful, possibly tinged with envy as well as regret. The same is true if the colleague is retiring – depending how close you are to retirement yourself. But what are those who worked on developing the comet lander Philae supposed to feel now their colleague faces “eternal hibernation” after a decision was made to give up trying to contact it?

After a decade-long journey through space, the Rosetta spacecraft has spent the past year less than 100km from the nucleus of comet 67P Churyumov-Gerasimenko, capturing some stunningly detailed images. But despite this wealth of visual evidence for researchers there is a lot we still don’t know about the comet - including why it is covered in organic material rather than just ice and what causes its powerful jets of dust and ice.