Four years ago, the European Space Agency (ESA) achieved something that seemed impossible. It caught a comet. It was an idea first conceived in the 1970s, but it wasn’t until some 30 years later that, in March 2004, scientists from across the continent launched Rosetta on a decade-long journey. Over the next four years, the spacecraft would swing around Mars, and then Earth three times, before stopping in deep space just beyond Jupiter. There Rosetta waited, in deep hibernation, for its rendez-vous with comet 67P/Churyumov-Gerasimenko. Then in 2014, ESA woke Rosetta from its slumber and sent it chasing after 67P. Eventually, in a manoeuvre that would make Evel Knievel blush, Rosetta’s lander, Philae, bounced down onto the surface of 67P, discovering that it was unlike anything on Earth. The data…
