A groundbreaking discovery, leveraging seismic data from NASA's InSight lander, has confirmed the existence of a solid inner core within Mars. This revelation challenges long-held assumptions about the Red Planet's internal composition and offers profound insights into the evolution of terrestrial planets.
For years, the prevailing scientific view suggested that Mars' core was entirely liquid. However, analysis of over 1,300 marsquakes recorded by the InSight mission between 2018 and 2022 has provided definitive evidence of a solid, spherical center. Scientists, including a collaborative team from the United States and China, utilized seismic waves that penetrated Mars' core to detect this inner structure. The findings, published in the esteemed journal Nature, indicate a solid sphere approximately 600 kilometers (about 373 miles) in radius at the planet's heart, enveloped by a liquid outer core.
This internal architecture of Mars bears a striking resemblance to Earth's, with the inner core comprising roughly one-fifth of the planet's total radius, mirroring Earth's own proportions. This similarity suggests that both planets may have undergone comparable processes during their early formation and cooling stages. The estimated composition of Mars' inner core includes iron and nickel, akin to Earth's, but is also significantly enriched with lighter elements such as sulfur (12-16%), oxygen (6.7-9%), and carbon (up to 3.8%).
The presence of a solid inner core implies that Mars experienced a cooling process analogous to Earth's, potentially leading to core crystallization. This finding is particularly significant given Mars' current lack of a global magnetic field. Scientists theorize that the planet once possessed a magnetic field, crucial for protecting its atmosphere and potentially supporting life, but this field dissipated over time. The newly confirmed core structure provides a critical piece of the puzzle, suggesting that Mars' core dynamics, including its crystallization rate, may explain the cessation of its magnetic dynamo. The slow crystallization of the solid core is now considered a likely reason for the planet's inability to generate a sustained magnetic field.
This discovery is a testament to the success of the InSight mission, which provided unprecedented seismic data. While earlier studies had hinted at a fully liquid core, the meticulous analysis of specific seismic wave phases, including those that bounced off a solid boundary, has now resolved this long-standing question. The findings not only deepen our understanding of Mars' geological history and its transition from a potentially habitable world to its current arid state but also offer a vital comparative framework for studying planetary evolution across the solar system.