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.
After a meticulous search, an ESA team has now discovered the previously unknown site of Philae’s second touchdown—and with it an imprint that the craft left in comet ice that is billions of years old.
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. “It’s softer than the lightest snow, the froth on your cappuccino or even the bubbles in your bubble bath,” says Laurence O’Rourke, an ESA scientist at the