Mars’ water mystery may have a simple ice answer

Small lakes on early Mars may have remained liquid for decades, even though the planet was very cold. New research suggests that cold conditions alone may not have prevented liquid surface water from existing on the Red Planet for long periods.

Researchers from Rice University used a climate model adapted for Mars. They wanted to see if lakes could have survived in places like Gale Crater near the planet's equator. Their results showed that lakes could stay liquid under a thin layer of seasonal ice for decades, possibly longer. This finding addresses a major question in Mars science. Many landscape features on Mars were shaped by flowing or standing water. Yet, many climate models say early Mars should have been too cold for liquid water to exist.

The study was published in the journal AGU Advances. It offers a new explanation for how lakes could have formed without a warm climate. It also helps explain why ancient Martian lake beds look so well preserved today.

"Seeing ancient lake basins on Mars without clear evidence of thick, long-lasting ice made me question whether those lakes could have held water for more than a single season in a cold climate," said Eleanor Moreland. She is a Rice graduate student and the lead author of the study. "When our new model began showing lakes that could last for decades with only a thin, seasonally disappearing ice layer, it was exciting. We might finally have a physical mechanism that fits what we see on Mars today."

To investigate this problem, the team used a climate modeling method called Proxy System Modeling. This approach was originally developed by Earth climate researcher Sylvia Dee. It is used to reconstruct ancient climates using indirect indicators like tree rings or ice cores.

Mars does not have trees or other familiar climate markers. So, the researchers used data collected by Mars rovers instead. Rock formations and mineral deposits served as a stand-in for a climate record. This allowed the team to guess what past conditions were like.