Mars Might Have Once Hosted Larger Moons

There may have been ancient tides on Mars, suggesting the presence of larger moons capable of influencing the planet’s waters. Currently, Mars has two small moons that aren’t sufficient for this theory.

Suniti Karunatilake and researchers from Louisiana State University discovered signs of tidal activity in Gale Crater’s sedimentary layers.

By examining these layers, they inferred the nature of the tidal cycles and the potential moon responsible for them. If such a moon existed, it would have been significantly larger than Phobos, Mars’ biggest moon, yet still smaller than Earth’s moon. The two current Martian moons might be remnants of a larger satellite.

Mr. Karunatilake is set to present the findings at the upcoming American Geophysical Union meeting in New Orleans, Louisiana.

The sedimentary rocks that supported their conclusions were captured by NASA’s Curiosity rover, displaying alternating layers of varying thicknesses and colors. These strata are termed rhythmite, indicating that they were formed by winds or ocean currents of fluctuating strength. In tidal scenarios, sand is transported back and forth, covered by fine mud when the tide recedes.

The rhythm of strong winds leaves thin, dark lines indicative of “mud drapes,” which “resemble Earth’s tidal patterns closely,” notes team member Priyabrata Das, also from Louisiana State University.

To bolster their hypothesis, Ranjan Sarkar from Germany’s Max Planck Institute for Solar System Research utilized a standard mathematical technique called the Fourier transform to evaluate the layered structures in Martian rocks. This analysis revealed additional periodicity in layer thicknesses, implying that both the sun and a past moon may have influenced the tides.

This analysis may validate the idea initially put forth by Rajat Mazumdar from the German Institute of Technology in Oman. In 2023, Mazumdar suggested that layered formations observed by NASA’s Perseverance rover in Jezero Crater could indicate tidal activity. Unfortunately, the resolution of these images was insufficient for Fourier analysis. Enthused by the Gail rhythmite findings, Mazumdar emphasizes that rhythmite on Earth is strong evidence of tidal conditions.

However, skepticism remains. The lakes in Jezero and Gale craters, sized at 45 kilometers and 154 kilometers respectively, are considered too small to exhibit significant tidal flooding. Nicholas Mangold, a member of NASA’s Perseverance Mars team at the Institute for Planetary and Earth Sciences in Nantes, France, argues that larger moons wouldn’t have left tidal traces in these locations.

Christopher Fed, a professor at the University of Tennessee working with NASA on the Curiosity mission, also finds the notion of a larger moon problematic, suggesting that tidal-like patterns could emerge from varying river inflows instead.

Nevertheless, Sarkar believes a tidal connection is feasible. “The ocean might have linked to Gale, and even subsurface porosity could create tides. Mars’ surface is extensively cracked and crated, meaning porosity isn’t an issue,” he argues.