The start of spring at the North Pole on Mars
The start of spring at the North Pole on Mars
A rare view of the northern polar region of Mars during spring. The upper half of the image, acquired in June 2019 by the High Resolution Stereo Camera (HRSC), shows the ice cap, which consists of water ice, to striking effect. In winter it is covered by a thin layer of carbon dioxide ice and then also covers large areas of the Vastitas Borealis plain (down to 70 degrees north). A dark, circumpolar ‘channel’ in the middle of the ice coverage marks the boundary between the permanent water ice cap and the layer of carbon dioxide ice. Within the space of a few weeks, this winter layer of carbon dioxide ice sublimates (transitions directly from solid to vapour) once again and the polar cap shrinks back to its summer extent, which extends to approximately 80 degrees north. A thin veil of cloud stretches over the vast dune fields made of dark sand.