SETI Institute Finds Remains of 'Modern' Equatorial Glacier on Mars

Mars was once a wet, potentially alive world, but a lot can change in a few billion years. Today it's a dusty, frigid wasteland bathed in a sea of cosmic radiation. Still, NASA plans to send humans to explore the red planet eventually, and the more we know about the terrain, the better. A new study from the SETI Institute has revealed evidence of recent water ice glaciers on the planet. This wouldn't be the first sign of water on Mars, but it is unique because it's nowhere near the polar regions. It's almost on the equator.

The team, led by SETI Institute researcher Dr. Pascal Lee, focuses on a "relict" glacier in the Eastern Noctis Labyrinthus region. That means it's a remnant of an earlier time, but scientists believe it's still relatively new for a geologically inactive world like Mars due to the lack of impact craters. The formation is not ice but a light-toned deposit (LTD) composed of sulfate salts. However, the structure of the salt formation screams "glacier."

This formation, as seen below in an image from the Mars Reconnaissance Orbiter, is enormous, measuring 3.7 miles (6 kilometers) long and 2.5 miles (4 kilometers) wide, with a height of up to 1.1 miles (1.7 kilometers). It's not just the size that suggests a glacial past, though. Lee points to shapes we associate with water ice glaciers, including tic-tac-toe-like crevasse fields and moraine bands (piles of debris pushed up by glacial formation).

Credit: NASA/SETI

Volcanic material covering much of the surrounding terrain suggests a potential formation mechanism for the salty glacial remnant. When pyroclastic materials like ash and pumice come in contact with water ice, they form a thick, crusty layer of sulfate salts. The study (PDF) suggests erosion slowly removed the volcanic material coating, revealing the salts. Therefore, the LTD in the Eastern Noctis Labyrinthus could be an imprint of the glacier that once stood there.

Since the formation likely originated in the geologically recent past, that could mean water ice was common near the equator much later than we previously believed. Water ice may still be buried close to the surface in the Eastern Noctis Labyrinthus. Any long-term human mission on Mars would benefit significantly from in-situ resource utilization, and that has pushed planners to consider regions closer to the poles where water ice is known to exist. However, the even more frigid temperatures at higher altitudes pose additional challenges. An equatorial region with accessible water could offer a desirable alternative. NASA is currently targeting the mid-2030s for the proposed Mars mission, so we've got time to figure it out.