When it comes to studying planets other than Earth, Mars is the most investigated. There are currently multiple rovers and spacecraft orbiting the Red Planet. One of the landers on the surface is the NASA InSight Lander. InSight uses seismic waves bouncing around the interior of Mars to measure the size of the molten core of the planet.
InSight has been on the surface of Mars since 2018 and has measured more than 500 marsquakes since it arrived. Scientists have noted that most of the marsquakes the lander has recorded have been relatively small. Two types of seismic waves have been measured with these events, including those that skim near the surface, traveling in a relatively straight line between the quake and the lander, and a type that bounces around within the planet before reaching the detectors.
InSight found in many of the records of marsquakes recorded by the lander a set of seismic waves with a shape that suggested they bounced off a boundary between the planet’s mantle and core. Those particular waves arrived at the detector about 500 seconds after the first surface tremors.
The team was able to use the time difference in the direction the waves arrived from to calculate the size of the core of Mars. The scientists estimate the core has a radius of about 1810 to 1860 kilometers. Researchers note that the size is at the high-end of the range estimated in previous work. The size also implies the core could be less dense than researchers previously believed, meaning the interior is richer in lighter elements like oxygen.
Currently, the location where the lander is on Mars is in the middle of dust storm season. The team expects to record more marsquakes in the coming months after the dust storms end, shedding more light on the planet’s structure.