ESA has published new images of Korolev crater on Mars obtained thanks to of its Mars Express space probe’s High Resolution Stereo Camera (HRSC) instrument. Its peculiarity is that it’s filled with water ice and despite the presence of dust its color is white, which is a strong contrast with that of the surrounding land. Normally water can’t remain solid at the very low pressure generated by the Martian atmosphere but near the north pole Korolev crater acts like a cold trap.