Lowell Crater - Mars Express
Mars Express HRSC image of Aonia Terra. This ancient region of the Martian highlands has accumulated a large number of craters, including Lowell Crater (203 km diameter; named after Percival Lowell) located at bottom center. The high density of craters attests to the ancient age of this region and generally quiet geological activity.
This region is located deep in the southern hemisphere midlatitudes. At the time this image was taken, Mars had just passed the southern hemisphere's winter solistice. This event also occurs when Mars is furthest from the Sun. Combined with the high altitude, these factors make this time of the Martian year exceptionally cold within this region. The effects of this cold can be seen by the large CO2 frost deposits that cover most of this picture.
This image was taken during Mars Express' 15,361st orbit of Mars, February 13, 2016. It uses a combination of blue and green filter images taken by HRSC in addition to a simulated red image derived from the blue and green channel data.
Image Credit: ESA/DLR/FU Berlin/J. Cowart, CC BY-SA 3.0 IGO