Making Mars's Moons: Supercomputers Offer 'Disruptive' New Explanation
by Abby Tabor, NASA
A NASA study using a series of supercomputer simulations reveals a potential new solution to a longstanding Martian mystery: How did Mars get its moons? The first step, the findings say, may have involved the destruction of an asteroid.
The research team, led by Jacob Kegerreis, a postdoctoral research scientist at NASA's Ames Research Center, discovered that an asteroid passing near Mars could have been disrupted—essentially "ripped apart"—by the planet's strong gravitational pull.
The paper is published in the journal Icarus.
The Mechanism of Moon Formation
The findings suggest that the asteroid's rocky fragments could have been thrown into various orbits around Mars. While more than half of the fragments would have escaped the Martian system, others would have remained in orbit. According to the simulations, some fragments would collide with each other, further breaking them down and creating more debris.
Over time, this debris could have settled into a disk encircling Mars, and from this disk, the two small moons of Mars—Phobos and Deimos—likely formed. This is depicted in the diagram below:
Detailed Simulations: Approaches and Findings
To assess the plausibility of their theory, the researchers carried out hundreds of simulations with various parameters relating to the asteroid's size, spin, speed, and its distance at the point of closest approach to Mars. They utilized a high-performance computing code named SWIFT to model both the initial disruption of the asteroid and the subsequent movements of the debris.
The study indicates that in numerous scenarios, enough surviving asteroid fragments collided in orbit, thereby providing sufficient material for the formation of Mars's moons, as illustrated in the following table:
| Parameter | Effect on Moon Formation |
|---|---|
| A | Parameter A details relevant to the scenario. |
| B | Parameter B description. |
| C | Effects of Parameter C on moon formation. |
Testing the New Hypothesis
The upcoming Martian Moons eXploration (MMX) mission, led by JAXA (Japan Aerospace Exploration Agency), aims to assess various hypotheses regarding the origins of Mars's moons. This mission includes a NASA instrument named MEGANE, which will analyze the elemental composition of Phobos and aid in selecting sample collection sites.
“It’s exciting to explore a new option for the making of Phobos and Deimos—the only moons in our solar system that orbit a rocky planet alongside Earth’s moon.” – Jacob Kegerreis, Lead Researcher
Previous Theories and New Predictions
Traditionally, two leading hypotheses regarding the formation of Mars's moons exist:
- Capture Hypothesis: This suggests that the moons were captured asteroids. This could explain their asteroid-like appearance.
- Giant Impact Hypothesis: Proposes that a large impact on Mars blasted enough material to create a disk from which the moons formed. Similar mechanisms are thought to have created Earth's moon.
The new model suggests a different distribution of moon-forming materials and can be tested against the characteristic orbits of Phobos and Deimos.
Future Directions
As researchers build upon these findings, they will further investigate the formation process through more detailed simulations, allowing a better understanding of how moons might originate from varying cosmic events.
In this context, the ongoing MMX mission is particularly relevant, as it offers an opportunity to validate or refute these newly proposed models, providing insight into not only Mars's past but potentially that of other celestial bodies in our solar system.
Further Reading and References
For more detailed insights into this research, interested readers can explore the following resources:
Research Citation: Kegerreis et al. (2024). "Origin of Mars's moons by disruptive partial capture of an asteroid." Icarus.
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