Split personality of Mars revealed in its striking features

Mars is a planet of dramatic contrasts. Roughly one hemisphere of the globe is rugged and ancient, scarred with craters that indicate its age. The other is smoother, having been shaped by lava flows that have covered the underlying rugged surface.

A recent image from the Mars Express spacecraft offers a vivid glimpse of these two faces in a region known as Acheron Fossae. This area lies between two massive volcanoes – Olympus Mons to the south and Alba Mons to the northeast.

Scientists from the European Space Agency (ESA) studied the new images to understand better how volcanic and tectonic activity once reshaped the Martian surface.

Ancient structures reveal tectonic past

The right side of the image reveals a network of long, trench-like structures known as grabens. These geological features formed on Mars when the planet’s crust was pulled apart by tectonic stress.

Huge blocks of land cracked, sank, and created deep troughs that are separated by ridges. The grabens formed nearly four billion years ago and stretch about 800 kilometers (500 miles) – roughly the length of Germany.

The crustal tension responsible for the grabens likely came from the shifting of Mars’s surface during periods of intense volcanic activity.

The presence of nearby volcanoes, such as Olympus Mons and Alba Mons, suggests a strong link between volcanic activity and surface deformation in this area.

Glaciers and lava shape younger plains

Just below the center of the image is a smooth region that marks the beginning of younger plains. These plains were likely formed by glacial movement and lava flows.

Close to the grabens, evidence points to rock glaciers – combinations of ice and rock – that flowed slowly over time. These glaciers appear to have crept away from the cliffs, leaving behind patterns that resemble waves lapping at a shoreline.

The movement ends in gently sloping piles of debris, known as “debris aprons,” that spread away from the cliff bases.

Older features of Mars

Zoomed-in 3D views highlight the grabens, glacial flow, and areas where lava poured over older features.

One clear example is a half-visible impact crater, about 28 kilometers (17 miles) wide, that is partially buried beneath a smooth lava field. This suggests the crater existed before the volcanic activity that resurfaced the terrain.

In the upper right of the main image, three cone-shaped peaks rise above the plains. These domes are likely volcanic in origin.

What’s fascinating is that the grabens slice through some of these features, indicating that the crust continued to stretch and shift even after the volcanic domes formed.

Powerful geological changes on Mars

Since launching in 2003, ESA’s Mars Express has been photographing Mars in color and 3D with high resolution. For over 20 years, it has offered scientists a window into the Red Planet’s layered history.

Today, the spacecraft continues to reveal how time, lava, and ice worked together to shape the Martian landscape.

The Acheron Fossae image is just one example of how Mars, though quiet today, was once a planet of powerful geological change.

A window into planetary evolution

Scientists continue to investigate areas such as Acheron Fossae in order to learn more about the forces that sculpted not just Mars, but rocky planets in general.

The Red Planet offers a special geological record. Mars does not have plate tectonics and has very little wind or water erosion, unlike Earth, so its surface features have been preserved for billions of years.

These historic landscapes are snapshots of planetary processes locked in time. By examining the cracks, flows, and plains of Mars, scientists can reconstruct how the planet cooled, stretched, and changed.

The fact that there are ancient grabens, glacial landforms, and volcanic plains indicates a complicated and energetic past, even though today the planet is geologically calm.

These findings also assist scientists in constructing improved models of the appearance of other planets in the distant past.

With additional missions in the pipeline, including future sample-return missions and eventual crewed missions, Mars will continue to provide new opportunities to study planetary history, climate evolution, and the possibility of ancient life.

Information for this article was obtained from an European Space Agency press release.

Image Credit: ESA

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