New Model Suggests Mars' Moons Formed From a Disintegrated Asteroid

NASA simulations propose that Mars' gravitational forces tore apart an asteroid, whose debris eventually coalesced into its moons, Phobos and Deimos.

Researchers from NASA and Durham University used advanced supercomputer simulations to explore how Mars' moons, Phobos and Deimos, may have formed from asteroid debris.
The study suggests that a large asteroid, passing too close to Mars, was torn apart by the planet's gravitational forces, scattering fragments into orbit.
Over time, these fragments collided and coalesced into the two moons, offering an alternative to prior theories of asteroid capture or impact debris.
The model explains the moons' near-circular orbits and varying distances from Mars, which earlier hypotheses struggled to reconcile.
Japan's 2026 Martian Moons eXploration (MMX) mission will collect samples from Phobos, potentially confirming this new theory or supporting other hypotheses.