Overview

• A peer-reviewed paper led by the University of Science and Technology of China reports direct seismic evidence for a solid inner core on Mars, published in Nature on September 3, 2025.
• Modeling of InSight data estimates the inner core’s radius at about 613 kilometers, enclosed by a liquid outer core.
• Researchers identified PKKP and PKiKP phases, with PKKP waves arriving 50 to 200 seconds earlier than expected for a wholly liquid core.
• The findings draw on 1,319 marsquakes recorded by InSight between 2018 and 2022, with authors noting single-station limits and calling for additional seismic coverage.
• The core is inferred to be iron–nickel with possible lighter elements such as oxygen, informing Mars’s thermal evolution and magnetic-field history.