The early solar system was a dangerous placeIllustration of protoplanets colliding in the early solar system. Before things settled into the current configuration, there were other cosmic snowballs vying for a spot on the solar system roster. When InSight peered into the red planet’s interior, it saw lumps up to 2.5 miles across, scattered throughout the mantle. Their survival to this day tells us Mars’ mantle has evolved sluggishly over billions of years. By analyzing the seismic waves as they move through a planet’s interior, scientists can map the planet’s composition.