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.

On November 19, the International Space Station (ISS) adjusted its orbit to avoid a fragment of space debris originating from a satellite that disintegrated in 2015, according to NASA reports. The maneuver raised the station’s altitude of approximately 250 miles (440 kilometres) above Earth, preventing the debris from coming within 2.5 miles (4 kilometres) of the orbital outpost. This marked the 39th avoidance action taken by the ISS since its initial launch in November 1998 and the first instance of 2024.

Space Debris: A Growing Threat

Data from NASA shows that over the years, the ISS has conducted multiple maneuvers annually to protect its crew and infrastructure from space debris, although 2024 has seen fewer incidents compared to previous years. Hugh Lewis, a professor of astronautics at the University of Southampton, explained in Live Science that while fewer evasive actions have been needed so far this year, this could change unpredictably, with sudden increases in collision risks potentially necessitating immediate responses.

Causes of Space Junk Proliferation

According to reports, increased solar activity during the current solar maximum cycle has been influencing the behaviour of space debris. Solar events, such as coronal mass ejections, cause Earth’s atmosphere to expand, creating drag that can alter debris trajectories. Additionally, deliberate satellite destruction tests, such as Russia’s anti-satellite (ASAT) test in 2021, have significantly contributed to the accumulation of hazardous debris. Four of the nine maneuvers conducted by the ISS since 2021 were linked to fragments from Cosmos-1408, a Soviet-era satellite targeted during the ASAT operation.

Mitigating Future Risks

Experts, including Lewis, have emphasised the importance of removing defunct satellites to limit debris growth. It was noted that proactive measures, such as deorbiting retired satellites, would reduce collision threats significantly. With the ISS scheduled for decommissioning in 2031, maintaining safe operations remains critical as the threat from space junk continues to escalate.

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.