A stunning new image from the European Space Agency (ESA) has revealed an ancient crater on Mars filled with dark, wave-like sand dunes that look almost as if they are made of metal.
Captured by the High Resolution Stereo Camera aboard the Mars Express spacecraft, the scene offers a striking view of one of the oldest landscapes on the Red Planet and provides new clues about the powerful forces that have shaped it over billions of years.
The image focuses on part of Kaiser Crater, a huge impact crater located in the ancient southern highlands of Mars in a region known as Noachis Terra.
This area is among the oldest on the planet and has been battered by asteroid and meteorite impacts for more than four billion years.
As a result, the landscape is covered with craters of different sizes, some with sharp edges that remain well preserved, while others have slowly worn down over time.
Kaiser Crater itself is about 180 kilometers (112 miles) across and several kilometers deep. A large ridge running through the image marks part of the crater’s southern rim. The deep basin created by the ancient impact has become an ideal place for sand to collect, forming one of Mars’ most impressive dune fields.
The dark ridges covering much of the crater floor are not rock or metal. They are giant sand dunes shaped by steady Martian winds over countless years.
Some of these dunes rise more than 100 meters (330 feet) above the surrounding ground. While some stand alone, many connect together to create long, flowing waves that stretch for several kilometers.
The dunes appear to have a shiny, metallic look because frost collects on the slopes that receive less sunlight. This thin layer of frost reflects light, giving the dunes their unusual appearance in spacecraft images.
Scientists found two main types of dunes inside the crater. One type is known as barchan dunes, which have a crescent shape and are commonly seen in deserts on Earth, including the Sahara and the Namib deserts.
The other type is called transverse dunes, which form long, nearly parallel ridges. Both develop when wind blows steadily from the same direction over long periods.
The winds in this part of Mars mainly blow from the west, pushing fine grains of dark volcanic sand across the crater floor. This sand is rich in volcanic minerals such as pyroxene and olivine. Even today, the dunes continue to shift slowly as the wind moves the sand, making them some of the planet’s most active landforms.
The crater also preserves evidence that water may once have played a role in shaping the landscape. In several places, wind has stripped away the surface, exposing lighter-colored clay-rich rocks. These types of rocks usually form when minerals interact with liquid water, suggesting that water existed here long ago.
Scientists have also spotted small gullies and narrow channels running down the walls of some craters. Many of these features were probably created by dry landslides, but some older ones may have formed when underground ice melted or buried groundwater caused the surface to collapse.
Mars Express has been studying the Red Planet since its launch in 2003. During more than two decades in orbit, the spacecraft has mapped Mars in remarkable detail, producing high-resolution color and three-dimensional images that have transformed our understanding of the planet.
The latest view of Kaiser Crater is another reminder that although Mars is now a cold and dry world, its surface still preserves the story of a much more active and complex past.
