An international research team, including Dr. Makito Kobayashi, project researcher, has revealed the long and dynamic history of ice accumulation on Mars.
Subsurface ice in the mid-latitudes of Mars represents one of the largest present-day water reservoirs, but its long-term variations and the factors influencing accumulation remain unclear. The team systematically surveyed more than 750 craters in the Martian mid-latitudes using high-resolution images from NASA spacecraft. They found that ice has consistently accumulated on the southwestern interior slopes of craters throughout geological time. The team attributes this pattern to local “cold traps” created by reduced sunlight and shadows. Crucially, the study revealed that ice accumulation occurred not just once, but in multiple, distinct events. Each event showed differences in the direction of the water vapor supply and the thickness of the ice deposit, which were linked to obliquity-driven climatic transitions.
The team integrated their findings with climate models and showed that around 640 million years ago, Mars was covered by thick and widespread ice. However, this ice gradually disappeared over hundreds of millions of years. During the latest accumulation event, about 98 million years ago, ice was deposited only in localized regions. This finding suggests Mars transitioned from a relatively wetter climate favorable for ice preservation to the cold, arid environment seen today, where ice is more difficult to sustain.
This research provides a new perspective on the link between long-term climate change and ice accumulation on Mars. The findings carry important implications for selecting future landing sites and for developing strategies for in-situ resource utilization. Beyond these practical applications, the results also deepen our understanding of planetary climate systems and offer valuable guidance in the search for past habitable environments and signs of ancient life on Mars.
Papers
Journal: Geology
Title: Long-term and multi-stage ice accumulation in the martian mid-latitudes during the Amazonian
Authors: Trishit Ruj, Hanaya Okuda, Goro Komatsu, Hitoshi Hasegawa, James W. Head, Tomohiro Usui, Shun Mihira, and Makito Kobayashi
DOI: 10.1130/G53418.1