NASA's InSight lander arrived in November 2018 and started listening for Mars' heartbeat, we learnt something really remarkable: Mars is rumbling. To date, InSight has detected hundreds of marsquakes – enough to give us a detailed map of the Martian interior. Tkalčić and his colleague, geophysicist Weijia Sun of the Chinese Academy of Sciences, wanted to look for quakes that might have gone unnoticed in the InSight data. They used two unconventional techniques, only recently applied to geophysics, to hunt seismic events in the InSight data. Based on nine templates of known marsquakes, the pair detected 47 new seismic events,...