Water is crucial for life, which is why researchers prioritize finding water sources when exploring other planets. Mars is of particular interest to astrobiologists due to evidence of historical water presence. The current surface of Mars is cold and arid, prompting scientists to investigate what happened to that past water. Studies have indicated that Mars has an active water cycle that produces clouds of water ice, but the existence of water on its surface remains unclear.

Recently, an international team of researchers employed high-resolution imaging and spectral photoanalysis to look for frost on Mars’ volcanoes. They analyzed around 4,200 images obtained using a technology known as color and stereo surface imaging technology from Cassis. This technology utilizes satellite imagery of Mars from the European Space Agency’s Trace Gas Orbiter. The researchers explained that they identified frost by searching for the blue wavelengths in blackcurrant data, as frozen surfaces reflect more brightly at these blue wavelengths of spectral light.

Through their analyses, the team located 13 frost regions across four volcanoes, including Olympus Mons, Seranius Solas, Ascleus, and Arciamontes. They observed images taken over a 12-hour period and noted that high frost concentrations appeared early in the morning on the edges and craters of Olympus Mons. In one crater alone, frost covered an area of about 4,500 km or 3,000 miles, akin to the size of Philadelphia. The researchers estimated that these frost deposits were quite thin, measuring around 10 microns thick, which is roughly one-tenth the width of a human hair.

Next, the team sought to determine if the frost was composed of water or carbon dioxide. Given that Mars’ atmosphere is predominantly carbon dioxide, it is possible for carbon dioxide to freeze. Similar to Earth, Mars has ice in its polar regions; the Martian polar ice caps consist primarily of carbon dioxide, with minor amounts of water. Thus, they theorized that the volcanic frosts could also contain frozen carbon dioxide.

The research team utilized Mars weather research and prediction models to calculate the surface temperature of a volcano over a 24-hour period. They determined that the minimum temperature was -190°F or approximately -120°C, which is too warm for carbon dioxide frost to form, as it typically requires surface temperatures below -200°F or -130°C. However, they proposed that these volcanic frost deposits are likely made of water, as they were found at -140°F or -95°C in the Martian atmosphere.

The researchers highlighted that these Martian volcanoes are among the tallest highland volcanoes in the solar system and located within the equatorial region of Mars. It’s generally not expected that water ice would form in equatorial volcanoes since the slopes and sides tend to be too warm for frost condensation. However, their climate model indicated that the unique topography of these volcanic craters created local weather patterns conducive to frost formation.

Finally, the team carried out further observations and climate model simulations of Olympus and Arciamontes to ascertain whether this frost can form solely during the day or throughout the night. They found that frost accumulated in both volcanoes during the early mornings of winter and spring but not in summer, indicating a seasonal pattern that might reflect variations in Martian temperatures.

The researchers concluded that Mars’ volcanoes produce about 150,000 tonnes, or 150,000,000 kilograms, of water frost daily. They suggested that this frost formation is likely influenced by seasonal atmospheric phenomena such as wind patterns and pressure changes. Studying these processes could help scientists determine the potential for life on Mars; nevertheless, they noted that additional research is needed to rule out direct volcanic water sources.

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