December 6, 2023

That mission may be over, but NASA’s InSight Mars lander is still discovering new things about the Red Planet. Scientists poring over the data have now directly observed the core of another planet for the first time, and found that it’s not quite what we thought.

The InSight lander is sent to Mars to study the planet’s interior, primarily through Marsquakes. As you might have guessed, these seismic tremors are similar to those on our planet, but since Mars doesn’t have plate tectonics, they’re usually much weaker. However, they can provide some clear insights into the structure and composition of the different layers beneath the red surface. Contact with the probe was lost in December 2022, but there is still much to glean from the data collected during its tenure.

In the new study, NASA scientists took direct observations of the Red Planet’s core thanks to two earthquakes on August 25 and September 18, 2021. These were the first events detected from the other side of the Earth, meaning their seismic waves had to travel farther to reach the detectors, passing through the core on the way.

Seismic waves travel through different materials and structures at different speeds, and changes in the data that eventually reach the detectors can leave their imprints along the way. This can tell scientists a lot about a planet’s interior.

In this case, the detections led the team to deduce that the core of Mars is smaller and denser than previously thought. While it’s mostly made of liquid iron, about a fifth is made up of elements like sulfur, oxygen, carbon and hydrogen.

“Determining the amount of these elements in a planet’s core is important for understanding the conditions in the solar system when planets formed and how those conditions affected the planets that formed,” said study co-author Doyeon Kim.

InSight may have completed its data collection, but existing data will likely continue to drive new discoveries for decades to come, the team said.

The study was published in the journal Proceedings of the National Academy of Sciences.

source: nasa