For millennia, humans could see Mars in the sky. Only in the last four centuries could telescopes reveal its surface features. Some features described early on – the ‘canals’ – were illusory. Space probes got us closer. Mars landers got us right there on the surface.
Only 7 years ago, the Insight Lander put a seismometer on the ground. The device detects tiny vibrations or ‘marsquakes,’, the exact yet weak Martian analog of terrestrial earthquakes. So, what’s the interest in detecting marsquakes?
Just as on Earth, seismic waves can travel deep into the planet. They can bounce to the far side of the surface and back. They can pass by the center, they can pass through the center. The strength of the signals at the seismometer and the travel times reveal the inner structure – just as on Earth. Mars has a solid core! Think of that. We now have some details of inner Mars.
It took rocketry starting with Chinese gunpowder rockets to modern rockets to exquisite calculations of rocket trajectories to amazing safe landings. It took about a century of experience on Earth to figure out how the seismic waves move and to reconstruct what that tells us about physical state, temperatures, and pressures so immensely deeper that we will ever drill. Congratulations to scientists, engineers, and an inquisitive, supportive public.
This has been an outreach activity of the Las Cruces Academy, viewable at GreatSchools.org.
Source: Nature, 4 Sept. 2025, 50-52
Image: From the article
