InSight Measures the Size of Mars’ Core

Martian water ice clouds drift over the dome-covered seismometer, known as SEIS, belonging to NASA’s InSight lander. Credits: NASA/JPL-Caltech. 

News from NASA’s InSight Mission on July 22, 2021 (source)

Before NASA’s InSight spacecraft touched down on Mars in 2018, the rovers and orbiters studying the Red Planet concentrated on its surface. The stationary lander’s seismometer has changed that, revealing details about the planet’s deep interior for the first time.

Three papers based on the seismometer’s data were published today in Science, providing details on the depth and composition of Mars’ crust, mantle, and core, including confirmation that the planet’s center is molten. Earth’s outer core is molten, while its inner core is solid; scientists will continue to use InSight’s data to determine whether the same holds true for Mars.

“It took scientists hundreds of years to measure Earth’s core; after the Apollo missions, it took them 40 years to measure the Moon’s core. InSight took just two years to measure Mars’ core.”

— Simon Stähler, ETH Zurich, lead author of the core paper

Each of the papers in Science focuses on a different layer. The scientists found the crust was thinner than expected and may have two or even three sub-layers. It goes as deep as 12 miles (20 kilometers) if there are two sub-layers, or 23 miles (37 kilometers) if there are three.

Beneath that is the mantle, which extends 969 miles (1,560 kilometers) below the surface.

At the heart of Mars is the core, which has a radius of 1,137 miles (1,830 kilometers). Confirming the size of the molten core was especially exciting for the team.

Size of Mars’ core (3,660 km diameter) compared to the planet as a whole (6,794 km), here imaged by ESA’s Mars Express spacecraft on Sept. 22, 2017

“This study is a once-in-a-lifetime chance,” said Simon Stähler of the Swiss research university ETH Zurich, lead author of the core paper. “It took scientists hundreds of years to measure Earth’s core; after the Apollo missions, it took them 40 years to measure the Moon’s core. InSight took just two years to measure Mars’ core.”

Read the full news release from NASA here.

Learn more about the InSIght lander, instruments, and mission in the video below: