Considering the Mars water discussion: Analysis challenges previous findings

Over three billion years ago, Mars had intermittently held liquid water on its surface. However, after the planet lost much of its atmosphere, surface waters could no longer last. The fate of Mars’ waters is buried like ice, trapped in deep aquifers, incorporated into minerals and dissipated into space.

Last week, in a letter to the editors of the minutes of the National Academy of Sciences (PNAS), Jakosky disputed the conclusion of the 2024 PNAS study, which suggests that Mars holds a substantial amount of liquid water in its bone. Jakosky points out that it is one possible conclusion, but not the only conclusion. This is because the underlying data for the study does not require a water-saturated crust.

“The approach and analysis are reasonable and appropriate, but the modelling results suggest alternative conclusions,” says Jakosky.

The data used in the analysis came from NASA’s internal exploration using the Geodesy and Heat Transport (Insight) mission, which began in 2018 and placed a single landing gear on Mars to collect geophysical data and study the interior of the planet. The mission ended in 2022, but when Mars’ dust storm obscured the solar panels of the lander, scientists still analyse the data from insights and debate what that means.

In the August 2024 PNAS study, Vashan Wright, a geophysicist at the Scripps Oceanographic Research Institute at the University of California, San Diego, and colleagues were able to determine rock physics models, rock levels, water saturation levels, and interpore spatial characteristics, explaining what was collected from areas collected from a confined area from a region from a region.

The team concluded that the central central skin, composed of fractured igneous rocks saturated with liquid water, “does best explain existing data.” They estimated that the volume of trapped water reached a depth of 1-2 kilometres. If it spreads evenly across the surface of the earth, it is a measure called the global equivalence layer. For comparison, the global equivalent layer of Earth is 3.6 km, almost entirely due to the ocean, with almost no water in the crust.

“We expect water and ice in the crust,” says Jakosky. “It’s challenging to actually detect it and perhaps determine its richness, but it’s very important to understand how much water there is on Mars and what its history is.”

A reexamination of Jakosky’s model results examined other conditions, such as the distribution of pore spaces and the presence of solid ice and empty pore spaces. The insight data does not require the presence of water in the center, but Jakosky says it does not rule out that. After considering the distribution of pore space, he concluded that the global equivalent layer ranges from 0 to 2 km, and concluded that it would expand the lower bound found in previous studies.

The amount of water present in the Mars crust is a question that may help answer someday further missions to conduct more detailed geological analysis and observations, including more advanced seismic profiling. Additional implications of the findings include a better understanding of the water cycle of the Red Planet, the potential conditions of life, and the availability of resources for future missions.