Review Article: Evidence for Transient Morning Water Frost Deposits on the Tharsis Volcanoes of Mars
Suvankar Majumder
Founder & CEO of Agnirath Aerospace and Defence Research Private Limited
Review Article: Evidence for Transient Morning Water Frost Deposits on the Tharsis Volcanoes of Mars
The Tharsis volcanic province on Mars has been a focal point for understanding the planet's current water cycle and its implications for habitability and future exploration. Recent high-resolution observations from the Colour and Stereo Surface Imaging System (CaSSIS) aboard the European Space Agency’s Trace Gas Orbiter have provided compelling evidence for transient morning water frost deposits on the calderas of the Tharsis volcanoes. This review synthesizes the key findings from these observations, highlighting the processes driving frost formation, its seasonal and diurnal variability, and its broader implications for Martian atmospheric and surface processes.
Mars' Tharsis volcanic province, with its towering volcanoes such as Olympus Mons, Arsia Mons, Ascraeus Mons, and Ceraunius Tholus, presents a unique environment for studying Martian climatology and geology. Water vapor and ice clouds above Tharsis suggest active water exchange between the Martian regolith and atmosphere. This review discusses recent evidence for morning frost deposits on Tharsis calderas and examines their formation, persistence, and disappearance, which are crucial for understanding Mars' water cycle.
High-resolution CaSSIS images revealed transient bluish frost deposits on the floors and rims of Tharsis volcano calderas during early morning hours in the colder Martian seasons. These frost deposits were absent by the afternoon, indicating a diurnal cycle. Complementary spectral observations and independent imagery from ESA’s Mars Express orbiter confirmed the presence of water frost rather than CO2 frost, which is also consistent with climate model simulations suggesting temperatures low enough to support water frost condensation but not CO2 frost.
领英推荐
The formation of frost on Mars is influenced by several factors, including local microclimates, topography, and surface properties. The frost deposits on Tharsis volcanoes are primarily atmospheric in origin, as volcanic outgassing is not seasonal. Early-morning surface temperatures at high altitudes, especially in the summit regions of these volcanoes, drop sufficiently to allow for frost condensation. The spatial correlation between frost deposits and specific topographical features, such as the caldera floor and rims, highlights the role of local thermal and moisture conditions.
The frost deposits exhibit clear diurnal variability, forming during the night and sublimating shortly after sunrise. Seasonal changes also impact frost formation, with deposits appearing predominantly during the colder seasons. These patterns are consistent with Mars' atmospheric dynamics, where water vapor is transported and deposited in colder regions during specific times of the Martian year.
The detection of water frost on Tharsis volcanoes has significant implications for the Martian water cycle. It suggests that even in equatorial regions, transient frost can form under favorable conditions, contributing to the localized exchange of water between the atmosphere and surface. This process plays a crucial role in the redistribution of water on Mars, potentially influencing the planet’s habitability and guiding future exploration missions.
The evidence for transient morning water frost on the Tharsis volcanoes provides valuable insights into the current Martian water cycle. These observations underscore the importance of high-altitude regions and local microclimates in water deposition processes. Future studies should focus on continuous monitoring and modeling to further elucidate the dynamics of frost formation and its impact on Mars' environmental and geological evolution.
Valantinas, A., Thomas, N., Pommerol, A., et al. (2024). Evidence for transient morning water frost deposits on the Tharsis volcanoes of Mars. Nature Geoscience. https://doi.org/10.1038/s41561-024-01457-7