The moons of Mars, Phobos and Deimos, could have formed from the remnants of an asteroid that was destroyed by the planet’s gravitational forces. Researchers from NASA and Durham University utilised advanced computer simulations to explore how such an event might have unfolded. These findings present a compelling new explanation for the origin of Mars’ two small moons, which have long puzzled scientists.

A New Model for Moon Formation

According to a study published in the Icarus Journal on November 20, a large asteroid, upon straying too close to Mars, crossed the planet’s Roche limit—a critical distance where tidal forces exceed an object’s structural integrity—leading to its disintegration. The resulting debris, according to simulations, would have gradually coalesced into Phobos and Deimos. Dr Jacob Kegerreis, a scientist at NASA’s Ames Research Center, stated in a statement that this new model offers an “exciting” alternative to previously considered theories about the moons’ formation.

Phobos and Deimos are unusual among the solar system’s moons. While their irregular shapes and small sizes resemble asteroids, their circular orbits, aligned with Mars’ equatorial plane, suggest they formed in orbit around the planet. Previous theories, such as their origin from impact ejecta or capture of asteroids, have struggled to fully explain their characteristics.

Simulations Provide Answers

Using Durham University’s supercomputers, researchers conducted hundreds of simulations, adjusting variables like the asteroid’s size, speed, and proximity to Mars. The results indicated that enough fragments could have survived to create a debris disk around the planet, eventually forming the two moons. Dr Jack Lissauer of NASA Ames explained in a press release that this model allows for efficient distribution of moon-building material, even from a relatively small parent asteroid.

Future Tests with MMX Mission

The Japanese Aerospace Exploration Agency’s (JAXA) Martian Moons eXploration (MMX) mission, launching in 2026, is expected to provide further insights. The mission will return samples from Phobos, which will be analysed for their composition. If similarities to Martian material are found, it may support the impact hypothesis, while asteroid-like material could validate this new model.

This research could also enhance understanding of planetary interactions with smaller celestial bodies across the solar system, opening doors to further exploration of moon and ring formation.

Planetary scientists have explored a hypothetical scenario in which a super-Earth existed within our solar system, situated between the orbits of Mars and Jupiter. According to recent simulations conducted by Emily Simpson and Howard Chen, planetary scientists at the Florida Institute of Technology, such a planetary configuration could have drastically destabilised the climates and orbits of neighbouring planets, including Earth.

Gravitational Instability and Climate Disruption

The findings, as per a Space.com report, highlight that super-Earths, which are commonly observed in exoplanetary systems, are notably absent from our solar system. These planets, larger than Earth but smaller than Neptune, are a frequent occurrence in the Milky Way. The researchers simulated various iterations of a super-Earth within our solar system to assess its gravitational effects on inner rocky planets like Earth, Venus, and Mars.

The study is said to have revealed that the presence of a super-Earth, particularly one with a mass ranging from 10 to 20 times that of Earth, would have caused significant disruptions. Chen stated in his interview with Space.com that the gravitational pull of such a planet could push smaller rocky planets into eccentric orbits or tilt their trajectories. These unstable orbits would lead to extreme climatic conditions, including erratic transitions between ice ages and periods of intense warming.

Chen told the publication that while the configuration we observe in our solar system is uncommon, the presence of a super-Earth in this region could have made Earth’s orbit highly unstable, jeopardising its habitability.

Implications for Life in Exoplanetary Systems

The findings suggest that even planets located in the habitable zones of other star systems may face significant challenges to sustaining life if they share their region with massive super-Earths. The instability introduced by such neighbours could hinder the evolutionary processes that require relative climatic stability.

While a slightly larger planet near Mars might lead to harsher seasonal variations on Earth, conditions for life could still persist. However, the researchers emphasised that the absence of a super-Earth near Mars and Jupiter may have been critical in enabling Earth’s current hospitable environment.

Efforts to uncover life on icy moons within our solar system have been bolstered by advancements in chemical modelling, according to recent reports. These models are being refined to better assess whether environments like Saturn’s moon, Enceladus or Jupiter’s moon Europa could support microbial life. Researchers aim to simulate the extreme conditions found on these celestial bodies to determine their potential habitability.

As outlined in the press release by Southwest Research Institute, Charity Phillips-Lander, Senior Research Scientist at Southwest Research Institute (SwRI), has emphasised the importance of accounting for organic compounds in such studies. Existing geochemical modelling tools often lack the capability to incorporate organics under the unique conditions of icy ocean worlds. Speaking to Space.com, Phillips-Lander stated that the question of habitability is about constraining the environmental factors that make it more likely to be friendly to life versus inhospitable.

Phillips-Lander and colleague Florent Bocher have developed custom software to simulate the formation and behaviour of organic-doped ice pores—microscopic structures formed under freezing and thawing conditions.

These phenomena, observed in laboratory analogues, are being used to replicate environments found on moons like Enceladus. The software’s ability to predict the interactions of organic compounds with ice under extreme temperatures and pressures provides key insights into potential microbial habitats.

According to the report, the team is focused on refining the tool to accurately model the chemical processes occurring in subsurface oceans beneath thick ice crusts. Enceladus is of particular interest due to its suspected water-rich environment and active plumes, which could indicate the presence of organic molecules.

Implications for Future Missions

The researchers have indicated that the refined models could serve as very important tools for interpreting data from future missions targeting icy moons. Phillips-Lander explained that the project aims to fill gaps in current datasets, enabling more accurate laboratory simulations and aiding in the identification of potential biosignatures.

Reports suggest that these efforts are expected to contribute significantly to understanding the habitability of icy worlds and support ongoing explorations of potential extraterrestrial life.