When the glacier roamed Mars

The surface of Mars is known for being extremely cold, dry and irradiated. However, as its many surface features demonstrate, the red planet was once a warm, damp place with water and glaciers. Today, most of the remaining water on the surface is largely confined to polar regions in the form of ice caps, permafrost, and underground glaciers. Nevertheless, this seasonal melting and freezing of ice still affects Mars’ environment and provides clues about past glacial activity.

In a recent paper, a team of scientists from the Institute of Planetary Science (PSI) investigated subglacial melting in and around the medium-sized craters of the Hart Lake System, a depression adjacent to the Terra region of Northern Arabia.

Based on multiple evidences, they propose that glaciers in retreating areas produced depression. Similarly, they argue that subglacial melting forms shallow waterways in the area, leaving a layered lake with small glacial deposits within the crater, leading to subsequent melting water and lake formation.

This paper was the subject of a presentation held at the 2025 Moon and Planetary Science Conference held in Woodlands, Texas from March 10-14, 2025. The authors are two senior PSI scientists, Dan Berman and Dr. Rebecca Me Williams. While Berman is a member of multiple studies in the NASA MARS Data Analysis Program and a team member on the Mars Reconnaissance Orbiter (MRO) mission, Williams is a member of multiple mission teams including the Rover of Patience and Curiosity, Mars, Mars, Mr, and Mars Global Surveyor (MGS).

As they show in their paper, the features formed in the presence of glaciers have been studied on Mars since the 1970s, starting with the Viking Mission. These features are interpreted as debris-covered glaciers due to their shapes consisting of leaf-like features, signs of deformation, linear structures, surface textures such as crevasses and pits. Tertiary moraines, ridge-like accumulations of glacial debris, have also been observed beyond them, indicating that they are experiencing ice loss.

As Berman explained in an email to Space today, “these glaciers are considered “cold-based.” This means that it does not melt with a base that promotes slide, as signs of melting such as melting water channels and escars are rarely observed. With its potential eskers (a tortuous ridge of sand and gravel formed by the melted glacial water), Mars emanates beyond the features of viscous flow, but the origins of these ridges are still debated. ”

These final features and hydrological models show that wet-based glaciers are possible, although evidence of subglacial melting is limited. To address this, Berman and Williams used Geographic Information System (GIS) technology to map these features. We also constructed a digital terrain model (DTM) based on global CTX and images taken by context camera (CTX) and high-resolution imaging science experiments (HIRISE) at NASA’s Mars Reconnasance Orbiter (MRO).

Their study focused on areas within and around the 48 km (30 miles) diameter crater of Terra and adjacent Heartlake System in northern Arabia. As Berman explained, this crater had previously been identified as a potential Paleolake.

“These include channels and hanging valleys that have melted into the terrace along the interior of the crater wall, similar to the post-glacial topography of the Alpine valley. The crater depicts caudal fans with valleys on the inner and outer walls and on the outer blankets, with the extension fans extending along the edge. Although it can also be interpreted as an inverted channel, it also provides evidence of a valley that escaped into the valley due to its sharp summit and slope.

Using GIS and its DTMS, Berman and Williams analyzed the topography and slopes of these features. Their results suggest that some of the valleys and ridges may have gone uphill, suggesting that they may be glacial of origin. These findings indicate that Mars may have been warmer than previously thought in the early days of Amazonian, the current geological age of Mars, which began 2.9 billion years ago. This has important implications for understanding Mars’ geological evolution and helps address the unresolved question of when Mars lost its water.

This provides a future exploration opportunity where robots and crew missions can observe these functions and determine whether they have been formed by melting ice.