Just below the surface, Mars is full of ice. New observations have revealed steep cliffs cut out of thick sheets of ice, which may be able to tell us about the planet鈥檚 climate over the past millions of years.
We know from previous radar studies that ice abounds just under Mars鈥檚 dusty surface, but where exactly it is in the Martian crust or how deep it goes is still unclear.
at the US Geological Survey in Flagstaff, Arizona and his colleagues examined pictures from the Mars Reconnaissance Orbiter and found eight ice patches in steep cliffs, which formed as ice accumulated over millions of years just under the Martian surface. Erosion revealed these icy blue spots, and they鈥檙e still visible today.
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The ice sheets start less than a metre below the surface and the team estimates that they are at least 130 metres thick. Of that, less than 100 metres is exposed, while the rest is below ground. Dundas says that they likely formed in layers as snow or frost built up on the surface and was compacted into ice over time as more frost and dust piled up. Studying the layers may help us learn about the history of Mars鈥� climate, as we do with ice cores on Earth.
Ice, ice baby
The area around these ice deposits lacks craters from meteor impacts, which indicates that the ice may be relatively fresh 鈥� deposited in the last few million years, rather than billion. That means that studying the individual layers can鈥檛 tell us about the time when Mars lost its atmosphere and liquid water more than 3.5 billion years ago, but it may be able to help us understand more recent developments.
鈥淥ver the past few million years, it鈥檚 thought that the tilt of Mars鈥� axis has varied between 15 and 30 degrees, so that affects the temperature at different areas on Mars, and that affects the deposition of ice,鈥� says Dundas. So, we can study the ice to learn about the planet鈥檚 temperature and how its tilt has changed.
Unfortunately, most of this study will have to be done from afar because the cliffs are quite steep. 鈥淭hey would be challenging to traverse,鈥� says Dundas. 鈥淚 don鈥檛 know if a rover could get there.鈥�
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Read more: It could be snowing on Mars right now
