The Planetary Science Institute reports on what space missions have learned from studying a strange, sinuous series of formations on the surface of Mars that resemble the curves and folds of brain coral. What they reveal, apparently, is a primeval history of glaciers moving across Mars:
“Mars currently has an axial tilt similar to the Earth – about 25 degrees – but it has undergone big shifts throughout its history,” said lead author and Planetary Science Institute Research Scientist Alex Morgan. “Millions of years ago, the tilt shifted and the poles were angled more toward the Sun. When that happened, the distribution of ice went crazy, and polar ice sublimated and the icy areas moved toward the equator.”
These brain coral terrains are thought to be the surface expressions of the remnants of debris-covered glaciers that formed far from the poles, in the mid-latitude regions of Mars.
To understand Mars’ climate history using these surface features, Morgan and his co-authors identified brain coral terrain in images acquired by the High-Resolution Imaging Science Experiment, or HiRISE camera, onboard NASA’s Mars Reconnaissance Orbiter using a machine learning algorithm developed by co-authors Kyle Pearson and Alphan Altinok at the NASA Jet Propulsion Laboratory. They then manually mapped brain coral terrain in Ismenius Lacus in the northern mid-latitudes of the eastern hemisphere, as well as Utopia Planitia and Arcadia Planitia, which are both found in Mars’ northern lowlands.
Next, they marked impact craters and determined how degraded those craters appeared to be. This information allowed them to determine the relative ages of the glaciers’ surfaces.
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Using crater degradation, they estimate that the surface deflation began about 25 million years and ended about 3 million years ago, during the Late Amazonian period. The deflation seems to correspond to a shift in Mars’ tilt from a dramatic 35 degrees to today’s 25 degrees. While ancient by Earth standards, this is young for Mars, as most of Mars’ most prominent features – such as lake deposits explored by the Curiosity and Perseverance rovers – are billions of years old.
“This suggests that craters were being degraded up until Mars shifted to its current state, and now things appear to be frozen in place,” Morgan said.
There’s a photo at the link.