The findings, published on July 22 across three studies in the journal Science, mark the latest scientific triumph for NASA’s InSight lander, which arrived at the flat equatorial plain known as Elysium Planitia in November 2018. The stationary spacecraft has measured faint “marsquakes” rumbling through the planet since early 2019.
On Earth, seismic waves can reveal our planet’s inner structure by revealing boundaries deep underground where the waves’ speeds and directions change. InSight’s similar measurements of Martian temblors have let scientists detect distinct layers within the red planet, including the boundary of its roughly 2,300-mile-wide core.
“As a seismologist, you probably have one chance in your life to find a core for a planet,” says InSight team member Simon Stähler, a planetary seismologist at the research university ETH Zurich in Switzerland, interviewed by video call.
Mars is just the third celestial body to have its core directly measured with seismic data, following Earth in the early 1900s and the moon in 2011. When combined with InSight’s first measurements of Mars’s mantle and crust structure, the core size will refine models for how Mars formed and changed over the past 4.5 billion years, from a possibly habitable world with liquid water and a planet-wide magnetic field to the hostile, rusty desert it is today. (Read more about humankind’s long-lasting obsession with Mars in National Geographic magazine.) READ MORE
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