A recent NASA study using advanced supercomputer simulations provides a fresh perspective on how Mars might have gained its two moons, Phobos and Deimos. The research suggests the process began with the destruction of an asteroid near the Red Planet.
Asteroid destruction sparks moon formation
Led by Jacob Kegerreis, a postdoctoral research scientist at NASA’s Ames Research Center, the study found that Mars’ gravity could have torn apart a passing asteroid. The resulting fragments scattered into various orbits around the planet. While some debris escaped Mars’ gravity, others remained, colliding and grinding down into smaller pieces.
These collisions likely created a disk of rocky material around Mars. Over time, this debris clumped together, potentially forming Phobos and Deimos.
Testing the hypothesis with supercomputer simulations
To assess the plausibility of this scenario, researchers simulated hundreds of asteroid encounters. They varied factors such as the asteroid’s size, speed, and distance from Mars. Using NASA’s SWIFT code and Durham University’s computing systems, the team analyzed both the asteroid’s initial breakup and the subsequent movement of its debris.
The findings, published in the journal Icarus, indicate that under many scenarios, enough fragments survived and collided to form the raw material for Mars’ moons.
Comparing competing theories of moon formation
Two primary theories have long dominated discussions about Mars’ moons:
Asteroid capture: This theory suggests that Mars’ gravity captured passing asteroids, which explains the moons’ asteroid-like appearance.
Giant impact: According to this model, a large collision with Mars ejected debris that eventually formed Phobos and Deimos.
While the giant impact theory better explains the moons’ near-circular orbits aligned with Mars’ equator, it doesn’t fully account for their positions far from the planet. The new asteroid disruption model bridges this gap, allowing for moon-building material to be distributed more efficiently to the outer regions of a debris disk.
A key test awaits: The Martian Moons eXploration (MMX) Mission
The upcoming Martian Moons eXploration (MMX) mission, led by JAXA, aims to resolve these questions. The spacecraft will study both moons and collect samples from Phobos to analyze their composition. NASA’s MEGANE instrument will identify the elements in Phobos’ surface, helping determine whether the moons originated from asteroids or a Mars-plus-impactor event.
Next steps in simulating moon formation
The NASA team plans to expand their simulations to study the entire timeline of moon formation in greater detail. Vincent Eke, a co-author and associate professor at Durham University, emphasized the goal of refining predictions for the MMX mission.
These simulations not only help us understand Mars’ moons but also provide insights into the broader processes of moon formation in our solar system. Such asteroid-planet encounters were common in the early solar system, offering a window into the evolutionary history of our cosmic neighborhood.
Source: NASA.
Image credit: NASA.
