It isn't every day that you get to hear the actual sound of a spacecraft touching down on a comet 310 million miles away.

As the Washington Post reports:

The Cometary Acoustic Surface Sounding Experiment (CASSE) sensors are located on the "feet" of Philae's three legs, and the two seconds of landing audio they picked up (which were taken during Philae's first impact, after which it bounced twice) are actually pretty interesting to researchers. They've analyzed the vibrations to tell them more about the comet's surface.

"The Philae lander came into contact with a soft layer several centimetres thick. Then, just milliseconds later, the feet encountered a hard, perhaps icy layer on 67P/Churyumov-Gerasimenko," Philae project scientist Klaus Seidensticker said in a statement. This is in line with what Philae's MUPUS tool found while hammering the comet's surface.

One small, crunchy thud for humankind.