Scanning for planetary cores with single-receiver intersource correlations

The network of seismographs on Earth allows us to gather enough data to reveal the properties of the metallic core hidden in the centre of the planet’s mantle envelope. In contrast, the small number of seismographs deployed on the Moon or Mars limits the sampling of their interiors and makes inferences challenging. Here we show that a single seismograph and global-scale waveform cross-correlations between seismic events can be used to scan planetary cores. We demonstrate that this technique allows us to constrain the sizes of the cores of Earth and Mars and we confirm that the Martian core is large. This technique provides an opportunity to investigate the structure of planetary interiors with currently realizable resources.