A new image captured by the Mars Express orbiter offers a striking view of one of the most heavily cratered regions on Mars.
The image shows part of Arabia Terra, a vast plain located in the planet’s ancient highlands, where billions of years of impacts have left the surface covered with craters of many shapes and sizes.
The photograph was taken using Mars Express’s High Resolution Stereo Camera, an instrument designed to capture detailed images of the Martian surface.
The view highlights a small portion of Arabia Terra, but even within this limited area there are numerous impact craters, each telling a story about the planet’s distant past.
Arabia Terra is one of the oldest regions on Mars. Scientists estimate that the surface here formed between about 3.7 and 4.1 billion years ago.
Because it is so ancient, the land has had plenty of time to collect impact marks from asteroids and other space rocks that collided with the planet long ago.
One of the most prominent features in the image is Trouvelot Crater. This enormous crater measures roughly 130 kilometers across. Its structure shows clear signs of age.
Over time, parts of its rim have eroded away, and the interior walls have collapsed in stages, forming terraced slopes that step down toward the crater floor.
Smaller craters have also formed on top of the original structure, further showing that the impact happened long ago.
Just to the left of Trouvelot Crater lies another large basin that appears even older. Its outer wall has been worn down so much that it is barely visible today.
Trouvelot’s impact partially cuts across this earlier crater, suggesting that the older basin formed first and was later disrupted by the impact that created Trouvelot.
Many of the craters across Arabia Terra contain dark deposits of rock. These rocks are rich in minerals such as magnesium, iron, pyroxene, and olivine.
Such mineral-rich rocks are known as mafic rocks and are often associated with volcanic activity. Scientists believe these materials may have been thrown up during ancient impacts and later redistributed by winds or gravity as material slid down crater walls.
Inside Trouvelot Crater, winds have shaped the dark material into crescent-shaped dunes known as barchan dunes.
These dunes form when winds blow mostly in one direction, gradually pushing sand into curved ridges. Similar dune patterns have been spotted in other regions of Mars, including near the planet’s north polar area and the volcanic region of Tharsis.
Among the dark rocks on the crater floor stands a lighter-colored mound about 20 kilometers long.
The mound is covered in ridges and grooves and stands out sharply from its surroundings. Similar features have been seen elsewhere on Mars, such as in Becquerel Crater.
These bright mounds are especially interesting to scientists because they often contain minerals that form in the presence of water. Some researchers think they may have developed in ancient lakes or seas that once filled Martian craters.
Others believe they formed as underground water mixed with wind-blown sediments over long periods of time.
Mars Express has been orbiting and studying Mars since 2003. During more than two decades of exploration, the spacecraft has mapped the planet’s surface in color and in three dimensions, helping scientists better understand the geological history of our neighboring world.
