Scientists have discovered evidence that liquid water once flowed in ancient, shallow lakes on Mars, challenging previous models that suggested Mars’ water was always covered by ice.

Using images from NASA’s Curiosity rover, researchers found wave ripples in Gale Crater lakebeds, indicating the water was exposed to the atmosphere and acted upon by wind.

These ripples suggest the lakes were shallow and less than 2 meters deep, forming around 3.7 billion years ago, Live Science has reported.

This discovery implies Mars may have had a warmer, denser atmosphere that allowed liquid water for a longer period, potentially supporting microbial life.

Written by B.C. Begley