NASA’s GRAIL Mission Reveals Moon’s Different Side

In May 2025, NASA’s Gravity Recovery and Interior Laboratory (GRAIL) mission uncovered key reasons behind the stark contrast between the moon’s nearside and farside, linking it to tidal deformation, volcanic activity, and crustal differences.

Key Points

GRAIL Mission Overview: Launched in 2011, twin spacecraft Ebb and Flow mapped the moon’s gravitational field with unprecedented precision, revealing details about its internal structure.
Tidal Deformation: The nearside of the moon flexes more due to Earth’s gravitational pull, making it warmer and more geologically active than the farside.
Volcanic Activity: The nearside experienced extensive lava flows billions of years ago, forming the dark basaltic plains (“mare”), fuelled by heat-producing radioactive elements concentrated in the mantle.
Crust Thickness: The nearside crust is significantly thinner than the farside, allowing magma to surface more easily, while the farside remains rugged and heavily cratered.
Thermal Imbalance: The nearside mantle is estimated to be 100–200°C hotter than the farside, shaping the moon’s geological evolution.
Future Exploration Impact: Understanding these differences aids development of precise lunar navigation systems and informs exploration strategies for other celestial bodies.
Earth Connection: The moon’s internal dynamics contribute to stabilizing Earth’s rotation and ocean tides, key factors in life’s evolution on our planet.