Mars Study Suggests Mid-Crust Water May Not Be Essential to Data Interpretation

Los Angeles CA (SPX) Mar 14, 2025
More than 3 billion years ago, Mars had episodic liquid water on its surface. However, as the planet lost much of its atmosphere, surface water became unsustainable. The precise fate of this water-whether locked in ice, stored in deep aquifers, incorporated into minerals, or lost to space-remains a subject of ongoing scientific inquiry. This debate has drawn particular attention from Bruce Jakosky, a senior research scientist at LASP and former principal investigator of NASA's Mars Atmosphere and Volatile EvolutioN (MAVEN) mission.

Jakosky recently addressed this issue in a letter to the Proceedings of the National Academy of Sciences (PNAS), contesting the conclusions of a 2024 study suggesting that Mars retains substantial liquid water in its mid-crust. While acknowledging the study's methodology as sound, Jakosky pointed out that its findings do not necessarily require a water-saturated crust, suggesting alternative interpretations of the data.

"The approach and analysis are reasonable and appropriate, but the results of their modeling suggest an alternative conclusion," Jakosky stated.

The study in question was based on data collected by NASA's InSight mission, which launched in 2018 and deployed a lander to study Mars' geophysical properties. Though the mission ended in 2022 due to a dust storm that depleted the lander's power supply, scientists continue to analyze its seismic and gravity data.

In their August 2024 PNAS paper, geophysicist Vashan Wright from the Scripps Institution of Oceanography at the University of California, San Diego, and colleagues applied rock physics models to determine possible compositions of Mars' mid-crust-located between 11.5 and 20 kilometers below the surface. Their findings suggested that fractured igneous rock saturated with liquid water best matched the observed data. The researchers estimated that, if evenly distributed, the trapped water could form a global equivalent layer (GEL) between one and two kilometers deep. For reference, Earth's GEL, dominated by its oceans, measures 3.6 kilometers.

Jakosky, however, argued that other factors-such as the arrangement of pore spaces and the presence of solid ice-could also explain the InSight data. By reassessing these variables, he determined that Mars' GEL could range from zero to two kilometers, broadening the lower limit set by Wright's team.

"We expect there to be water or ice in the crust," Jakosky explained. "Actually detecting it and possibly determining its abundance is challenging, but extremely important for understanding how much water there is on Mars and what its history has been."

The question of how much water remains in Mars' crust is likely to be addressed by future missions capable of more detailed geological analyses, including advanced seismic profiling. A clearer picture of the Red Planet's water reserves could deepen our understanding of its hydrological history, its potential for past or present life, and its suitability as a resource for future exploration efforts.

Research Report:Results from the InSight Mars mission do not require a water-saturated mid-crust