Mars contains no liquid water, but it does contain a considerable quantity of ice. One of the spots this can be seen is at the Korolev impact crater which is located in the northern lowlands of Mars, not far from the large dune field of Olympia Undae that surrounds part of the north polar ice cap. This Marsian, year-round ice reservoir has recently been captured by satellite photography – the Mars Express High Resolution Stereo Camera (HRSC).
The Korolev crater is named after the Russian rocket engineer and spacecraft designer Sergei Pavlovich Korolev (1907–1966), the chief constructor and father of Russian space technology. He is most famous for putting the first artificial satellite, Sputnik 1 (Russian for companion) into space back in 1957. That paved the way for the first manned space flight in 1961.
The crater goes down to 2 kilometres deep beneath its rim. Within its void is a 1.8-kilometre central mound of water ice all year round. That’s 2200 cubic kilometres of non-polar ice which is about 50 times the volume of Lake Constance and is comparable in size to the Canadian Great Bear Lake. Scattered around the crater’s edge are smaller amounts of ice water in the form of thin layer’s of frost.
Kirsten Siebach, a planetary geologist at Rice University in Houston, told NBC News MACH:
“There used to be liquid water in rivers and lakes on Mars, but it largely either froze as the atmosphere dissipated or was lost to space about 3 billion years ago. Ice still exists on Mars near the poles, and the Martian atmosphere has a tiny amount of water vapor.”
Depending on the season, the mixture of carbon dioxide and water ice found at the planet’s two polar caps varies greatly in proportion to one another. This means that the substance undergoes a direct transition from solid to gas from one season extreme to the next. For example, in the winter time, a one to two-meter layer of carbon dioxide ice (dry ice) forms on the permanent ice cap at the north pole, then sublimates again in summer, evaporating into the air.
This crater differs in the fact that it remains as solid ice all year round. The ice here is permanently stable because the depression acts as a natural cold trap shielding the ice with a blanket of dense cold air. Here’s how that works:
- The ice cools the air above it making it heavier than the warmer air around it.
- As it is heavier it sinks and remains there above the ice protected by the top of the crater walls.
- Since air is a poor conductor of heat it becomes a barrier that shields the ice from the environment and protects it from warming and evaporation.
Korolev Crater is about 51 miles (82 km) across so the images you see are actually a montage composed of five different “strips”, each obtained during a different orbit, then combined to form a larger single image. It was the European Space Agency (ESA) acquired the images via its Mars Express orbiter which has been circling the Red Planet for the past 15 years. ESA posted the image on December 20, 2018.