© ESA
A massive impact crater dominates a new view from the ExoMars Trace Gas Orbiter (TGO). The result of an ancient asteroid impact, the crater is located in Mars’ Utopia Planitia. That’s the largest known impact basin in the entire Solar System, with a diameter of roughly 3,300 kilometres (2,000 miles), or twice the size of Earth’s Sahara Desert from north to south. Interesting ice-related features on and below the surface of the crater give insight on the Red Planet’s watery past. “This remnant of an ancient impact is just one of the many scars asteroids have inflicted upon the Red Planet,” European Space Agency (ESA) officials said. “Water, volcanoes and impacts from asteroids shaped the Martian surface in the ancient past. Mars is currently a cold, dry desert.”
The recent image was taken by ExoMars’ Colour and Stereo Surface Imaging System (CaSSIS) from a distance of only 400 kilometres (248 miles) above the crater. From this vantage point, the crater nearly fills the camera’s entire field of view. The Utopia Planitia region is known to exhibit icy features, including frost on its surface during the Martian winter. The crater, stretching roughly eight kilometres (five miles) across, also shows signs of material ejected in a way that suggests there was water ice present when the asteroid hit the region in the distant past. Immense heat generated by the impact would have melted the water ice and forced the resulting mixture of liquid water and dust upward. “The smooth look of the crater is consistent with other features in the region having evidence of a water-ice history,” ESA officials said. “Zooming into the crater, it’s possible to see streaks on the walls of the crater, showing evidence of landslides, and ripples sculpted by the wind.”