Mercury’s Surface Holds Less Silica Than Expected, Hinting at Deeper Magma Origins

Key points

• Researchers from the Max Planck Institute for Solar System Research and German universities determined Mercury’s silicon dioxide content is about 37% by mass, significantly lower than prior estimates.
• The study utilized a three-step method: laboratory calibration with glass beads, validation using lunar infrared data and samples, and application to Mercury’s infrared observations.
• The lower silica abundance implies Mercury’s volcanic activity involved magma that melted more deeply within the planet, indicating a hotter interior than previously thought.
• ESA’s BepiColombo mission, scheduled to enter Mercury orbit in November 2026, will provide higher-resolution infrared data to verify these findings.
• The research also produced the first global map of silicon dioxide content on the Moon, confirming the method’s accuracy against samples from Apollo, Luna, and Chang’e missions.

Background

Previous studies, such as those from NASA’s MESSENGER mission (2011-2015), established that Mercury’s volcanic activity ceased approximately one billion years after the planet formed, leaving a solid crust. Earlier estimates of Mercury’s silica content were derived from remote sensing but lacked the precision of the new laboratory-calibrated method. The current study builds on this background by refining the relationship between infrared radiation and silica content, offering a more accurate baseline for future analysis.

How outlets are covering it

All three sources agree on the core finding that Mercury’s silica content is lower than previously thought, but they emphasize different aspects. SciTechDaily focuses on the methodological breakthrough and the implication of a hotter interior. Universe Today highlights the geological implications, noting that low silica suggests more powerful volcanism and links silica content to magma viscosity. Sci.News introduces a unique perspective, suggesting that some silicon on Mercury might exist in metallic or carbide forms rather than typical silicate minerals, a hypothesis not mentioned in the other two sources. All sources acknowledge the limitations of remote sensing and the importance of the upcoming BepiColombo mission for verification.

Why it matters

Understanding Mercury’s silica content provides critical insights into the planet’s thermal history and volcanic processes. The findings challenge existing models of planetary cooling and crust formation, suggesting that Mercury’s interior remained hotter and more active than previously assumed. This knowledge is essential for interpreting data from the BepiColombo mission and for understanding the formation of other rocky planets, including potential exoplanets observed by the James Webb Space Telescope.

What to watch

ESA’s BepiColombo spacecraft is scheduled to enter Mercury orbit in November 2026, with its two probes separating on September 3, 2026. The MERTIS instrument will collect high-resolution infrared data to verify the low silica abundance. Researchers aim to use this data to refine the silicon dioxide map and confirm whether the low silica is due to deep melting or oxygen loss over time.