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The seismometer was working well, they found: It was picking up background vibrations, called microseisms, in the martian surface that were induced by wind.

Conversely, on Earth, microseisms are caused by the ocean, storms and tides.

Although the microseisms are a thrill to hear, everyone working on InSight is waiting for the main event: their first marsquake.

This is the first time, he said, that such microseisms have been detected on another planet.

In the case of microseisms, both signals are faint but P waves have been more straightforward to study.