Martian sands offer a new way to reconstruct the planet’s ancient climate

Humanity has always been fascinated by the geography and climate of Mars. The possibility that Mars harbored canals captivated people for nearly half a century after initial (and erroneous) reports about them in 1877. In 2012, NASA’s Curiosity probe found evidence that water had been flowing into Gale Crater millions of years ago. In May, the Perseverance rover began a mission aimed at answering perhaps the biggest question about the Red Planet: whether the planet was ever – or still is – capable of harboring life.

Unraveling the mysteries of the planet’s ancient past is the key to understanding not just Mars, but how planets in general change over time. A study recently published in geology It examined the landscapes of Mars and how it evolved over the ages, providing new clues to exactly how and when erosion formed the planet, and when everything turned into a dusty desert.

Craters on Mars are the “dominant basin of windswept sediments on Mars today”. The planet’s lack of plate tectonics comparable to anything seen on Earth also means that much of the sediment and sedimentary rocks that make up it are not eroded by surface shift, allowing scientists to use craters as a tool to look into the distant past.

By examining these “basins” and comparing the amount of sand at each site with climate simulations, ice surface maps, and other factors such as the estimated age of the drilling, the authors can estimate how well wind-blown sand moves through the area. the surface of Mars for eons.

Gaze at the ancient climate of Mars

The authors analyzed data sets from 3,662 individual dune fields, which are large assemblies of dunes spanning the landscape, and 384,278 impact pit records to determine where craters and dune fields are located in the same location. The volume of sand sediments in those pits was then calculated, taking into account other factors such as climate and age as well.

For a given climate, which can change with latitude on Mars just as it does on Earth, the estimated thickness of dust in a crater can give insight into when rocks in certain regions were experiencing certain erosion patterns.

Study authors wrote:

Current dune fields accumulate over thousands of years but can be obtained from rocks that have eroded over much longer periods of time. As a result, these sediment accumulations present a unique opportunity to better understand past and present Martian surface environments.”

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The results indicate that there have been long periods of time when erosion was occurring much more rapidly on Mars than usual. Perhaps most importantly, evidence from some of the craters indicates that during the Late Noachian and Early Hesperian periods – roughly 4,000 to 3,000 million years ago – the rate of erosion on Mars was remarkably high, suggesting that water may have flowed at the surface at that time .

This is easy to understand when you consider how quickly rock erodes when exposed to water and only when exposed to air. The accumulation of sand and dust in those craters formed during that era.

As the authors explain to Phys.org:

“Our study quantifies the timing and rates of sediment erosion and buildup over the course of Mars’ geological history in an entirely new way, and for the first time quantifies the erosion scale of every type of rock we see on Mars. It is significant because we show that the abundance of wind-blown sand in craters on Mars They can be linked to the planet’s climate history, opening a new way to understand when Mars was habitable in geologic time.”

These findings help shed light on how Mars, a planet once thought to resemble Earth and possibly capable of harboring life, turned into the rusty desert that we find all the more remarkable today.

Perhaps one day, these findings could help us reshape the landscape on Mars.