Mars’ Glaciers Are Mostly Pure Water

Recent studies confirm that Mars’ glaciers are composed of over 80% pure water ice, with only a thin surface layer of dust and rock. This overturns earlier beliefs that Martian glaciers were mostly rocky debris with limited ice content.
 
Modern radar surveys and analyses, especially using instruments aboard NASA’s Mars Reconnaissance Orbiter, detected that glacier-like features across Mars’ mid-latitudes contain mostly pure water ice beneath a shallow debris cover. This purity of over 80% water ice has been found consistently across multiple sites and hemispheres on Mars, suggesting a uniform glacial history and preservation process. The thin debris layer shields the ice from sublimating into space, preserving Mars’ significant water reserves beneath the surface. The high purity and widespread distribution of Martian glacier ice offer valuable resources for future human exploration and colonization. This finding means Mars had a colder and wetter climate in its past, possibly experiencing one or several ice ages that shaped these glaciers.
 
The only partial disagreement comes from older literature, which assumed high rock content based on surface appearance and inconsistent earlier data. However, recent and more comprehensive radar studies strongly support the dominance of pure water ice in Martian glaciers.
 
References
​(2025, July 30). Mars glaciers Are Way More Water Than We Thought. Here’s Why It Matters. NASA Space News. https://nasaspacenews.com/2025/07/mars-glaciers-are-way-more-water-than-we-thought-heres-why-it-matters/
 
(2025, July 4). Glaciers on Mars. In Wikipedia, https://en.wikipedia.org/wiki/Glaciers_on_Mars
 
Ralls, E. (2025, July 28). Previously Believed To Be Mostly Rock, Mar’s Galciers Shown To Be 80% Pure Ice. Earth.Com.