NASA Reveals Secrets of the Moon and Asteroid Vesta's Interior with New Gravitational Analysis

The U.S. National Aeronautics and Space Administration (NASA) has revealed fascinating new details about the internal structures of our natural satellite, the Moon, and the massive asteroid Vesta. The findings, published May 14 in the scientific journal Nature, are based on a reanalysis of gravity data collected by previous space missions, demonstrating the power of this technique to explore distant worlds without landing on them.

In the lunar study, scientists developed a new model of the Moon's gravity that incorporates subtle variations detected during its elliptical orbit around Earth. These fluctuations cause the Moon to "flex" slightly due to the tidal force exerted by our planet, a process known as tidal warping. Analysis of this warping revealed that the near side of the Moon (the one we always see from Earth) flexes more than its far side.

The most likely explanation for this asymmetry in flexibility is the presence of a region of warmer mantle with a higher concentration of heat-generating radioactive elements deep in the near side.

This discovery provides the strongest evidence to date that intense and prolonged volcanic activity, occurring some 2 to 3 billion years ago, was responsible for the formation of the vast lunar "seas" (large, dark basaltic plains) and the accumulation of these radioactive elements in the underlying mantle on that lunar side.

This deeper understanding of lunar asymmetry is crucial to understanding the geological evolution of our satellite. In parallel, the NASA team applied a similar approach to study the asteroid Vesta, one of the largest objects in the asteroid belt.

By analyzing Vesta's rotational properties, particularly its slight "wobble" as it spins, and by precisely measuring its moment of inertia (a characteristic sensitive to how mass is distributed within it), the researchers came to a surprising conclusion.

Contrary to the idea that Vesta has a distinct, layered internal structure, like an onion (with a dense core, a mantle, and a crust), the new data suggest that the asteroid is much more homogeneous than previously thought.

Its mass appears to be more evenly distributed, with a very small or even nonexistent core of dense material. This finding challenges traditional differentiation models for large asteroids and could imply a different formation history for Vesta, perhaps originating from the debris of a catastrophic impact between early planetary bodies.

Both investigations highlight the growing sophistication and utility of gravity measurements made from orbiting spacecraft. This remote gravimetry technique is becoming an indispensable tool for probing the invisible interior of planetary bodies, offering a less expensive and risky alternative to missions requiring landings and drilling.

These discoveries not only refine our understanding of how the Moon and asteroids formed and evolved, but also provide valuable insights into the processes that shaped our own planet and the solar system as a whole.