The chaotic crash-landing of a robotic spacecraft called Philae has yielded serendipitous insights into the softness of comets. In 2014, the pioneering European Space Agency (ESA) lander touched down on comet 67P/Churyumov–Gerasimenko, after a ten-year journey aboard its mothership, Rosetta. But rather than fix itself to the surface, Philae bounced twice and ended up on its side under a shady overhang, cutting its mission short. The imprint has allowed the researchers to measure the strength of ice beneath the comet’s surface—and they discovered that it is exceptionally soft. “This is the icing on the cake.”This article is reproduced with permission and was first published on October 28 2020.