The InSight rover reveals a new map of Mars' interior. Its core is enveloped by a layer of molten rock. Measurements and analysis carried out in 2021 by NASA's now-retired InSirst rover. Scientists found that the Martian core is not composed only or practically only of iron, but also contains sulfur and oxygen, which are light elements. Scientists say that the core has a higher proportion of lighter elements than is feasible, based on estimates that had been made of the abundance of these elements.