The crater Korolev is 82 kilometers in diameter and in his depression maintains an ice disc that is seen in the images of the High Resolution Stereo Camera (HRSC) of Mars Express, the AEE's mission.
The photo published last Thursday was formed with five "stripes" captured in different orbits and combined to form a single image. In shots you can see whats about a well preserved crater covered with snow and full of ice.
Located in the lowlands of northern Mars, the crater is a depression south of Olympia Undae, a vast land dotted with dunes that surrounds the north pole of the red planet.
But how did the eternal ice form inside the crater? For a "cold trap" that forms at the bottom of the depression of 2 km. The snow at the edge keeps the temperature low enough so that it does not thaw.
The photos are dated April 28, 2018.