Discover the Hidden Connection That Could Reveal Mars’ Transformation into a Desert World

Scientists have known for a long time that ancient rivers shaped Mars, but how water moved between the surface and underground remains a mystery. A recent study from The University of Texas at Austin has shed light on this connection. Researchers found a significant link between surface rain-fed lakes and a groundwater reservoir about a mile beneath Mars’ surface.

The study, published in Geophysical Research Letters, was led by Mohammad Afzal Shadab and Eric Hiatt. They used a computer model to figure out how fast water seeped into Martian soil. Their findings indicate that water traveled from the surface to the aquifer over 50 to 200 years. While this timeline seems slow compared to Earth, where water can move underground in days, it makes sense given Mars’ deeper water table and different climate conditions.

This research provides the first numerical estimate of how long groundwater took to move during Mars’ wetter era, around three to four billion years ago. The model suggests that around 90 meters (300 feet) of water might have been lost underground, which is a significant part of the planet’s early water supply. Early Mars possibly had oceans several hundred meters deep, meaning much of that water is now hidden underground.

In contrast to Earth, where surface water cycles through evaporation and precipitation, Mars’ water seems to have vanished once it seeped below. As Eric Hiatt explains, "Once water got into the ground on Mars, it was as good as gone." This suggests that surface water on Mars drained quickly and became trapped in rocks, while the thin Martian atmosphere allowed water vapor to escape into space. This one-way journey of water significantly differs from Earth’s ongoing water cycle.

As Mars lost its atmosphere, the underground water either froze or became bonded with rocks as hydrated minerals. This hidden groundwater is not just a key to understanding Mars’ history; it might also be useful for future human explorers.

To study this, researchers modeled early Martian soil as a porous layer above a bedrock made of basalt. They considered factors such as temperature, gravity, and soil characteristics from meteorites and rover missions. Their algorithms revealed that water seeped in at different rates, largely influenced by Mars’ lower gravity, which allowed the pressure to build more slowly. The cooler temperatures also reduced evaporation, slowing the flow of water compared to Earth.

Their findings align with other observations, such as the presence of hydrated minerals in Mars’ crust and signs of buried ice. Studies have shown that more than half of Mars’ original water evaporated, but this research quantifies how much water moved underground and became trapped.

Moving forward, Shadab, now at Princeton University, aims to merge this infiltration model with global climate simulations. This work could help simulate different scenarios, from long-lasting oceans to floods caused by volcanic activity. Future Mars missions may attempt to drill deeply enough to sample these ancient aquifers directly. Analyzing the isotopes could help scientists understand how much water is still locked underground and how much has changed over time.

As Eric Hiatt notes, “The Red Planet’s hydrologic engine lacked the robust recycling pump that powers Earth’s blue marble.” Understanding this difference enhances our insight into Mars’ watery past and lays the groundwork for future explorations of its hidden water sources.

For a deeper dive into Mars’ geology and potential for life, you can read more from NASA’s Mars exploration program here.

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