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See the crater scar left on Mars by an ancient impact

The surface of Mars is dotted with craters, created when asteroids, meteoroids, or comets smashed into the planet and caused large impact marks. Unlike Earth, which has relatively few impact craters because of its tectonic processes, on Mars, these craters remain for billions of years.

An image of one such crater was captured from orbit by the European Space Agency (ESA)’s Mars Express spacecraft on April 25, 2022, and was just recently released. The image shows a large crater, nearly 19 miles across, in a region called Aonia Terra.

This image from ESA’s Mars Express shows part of the scarred and colourful landscape that makes up Aonia Terra, an upland region in the southern highlands of Mars.
This image from ESA’s Mars Express shows part of the scarred and colorful landscape that makes up Aonia Terra, an upland region in the southern highlands of Mars. ESA/DLR/FU Berlin, CC BY-SA 3.0 IGO

The landscape around the crater shows channels gouged into the surface, which were likely created when water flowed in rivers across Mars billions of years ago. “The channels appear to be partly filled with a dark material, and in some places, seem to actually be raised above the surrounding land,” ESA writes. “There are a variety of possible explanations for this. Perhaps erosion-resistant sediment settled at the bottom of the channels when water flowed through them. Or perhaps the channels were filled in with lava later on in Mars’ history.”

The image was taken using Mars Express’s High Resolution Stereo Camera (HRSC), and is a true-color image meaning it shows what a human eye would see. The data collected was also used to create a 3D terrain model, which allowed researchers to generate a view of the crater from a different angle as well:

The scarred and colorful landscape that makes up Aonia Terra, an upland region in the southern highlands of Mars.
This oblique perspective view of part of the scarred and colorful landscape that makes up Aonia Terra, an upland region in the southern highlands of Mars, was generated from the digital terrain model and the nadir and color channels of the High Resolution Stereo Camera on ESA’s Mars Express. ESA/DLR/FU Berlin, CC BY-SA 3.0 IGO

Studying impact craters is important as it allows scientists to estimate the geological ages of various features on the planet. The Aonia Terra region in the southern hemisphere is an excellent place for such research as it boasts many large craters, including the Lowell crater which is over 120 miles across.

The Lowell crater is named after Percival Lowell, an astronomer in the 1800s who famously thought that he observed canals on Mars, leading to an explosion of interest in the idea of life on Mars among the public. Although his theories were disproven and his observations turned out to be optical illusions, Lowell continues to have an influence both in science fiction writing and on science thanks to his passion for building observatories.

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