ESA/DLR/FU Berlin, CC BY-SA 3.0 IGO
While the presence of liquid water on Mars is still an ongoing topic of intense interest, we know that there's plenty of water ice adorning the Red Planet - and it looks amazing, as new pictures from the European Space Agency's Mars Express attest.
The Mars orbiter has obtained a mesmerizing view of a feature called the Korolev crater, an 81.4-kilometer (50.6-mile) diameter crater south of the Olympia Undae dunes circling the northern polar cap. The crater is filled with pristine ice year-round almost to the brim.
Like Earth, Mars has seasons. And like Earth, the warmer seasons result in receding ice. However, Korolev crater, created by a massive impact sometime in Mars's distant past, and named for Soviet rocket engineer Sergei Korolev, is a bit of an oddball.
It is a type of geological feature known as a 'cold trap,' and that is exactly what it sounds like. The floor of the crater is very deep, just over two kilometers (1.2 miles) below the rim. From the floor of the crater rises a dome of water ice, 1.8 km (1.1 miles) thick and up to 60 km (37.3 miles) in diameter.
In volume, it contains approximately 2,200 cubic kilometers (528 cubic miles) of ice (though an unknown proportion of it is probably Mars dust).
ESA/DLR/FU Berlin, CC BY-SA 3.0 IGO
A topographic map of Korolev crater. (ESA/DLR/FU Berlin, CC BY-SA 3.0 IGO)
When air travels over the ice, it cools and sinks, leading to a layer of cold air that sits directly above the ice. Since air is a poor conductor of heat, the cold layer acts as an insulator which protects the ice from warmer air and therefore preventing it from melting.
The same dynamic is at play in the much smaller 36-kilometre (22.4-mile) Louth crater, in the northern polar region of Mars too.
Mars Express - that celebrates its 15th anniversary in Martian orbit on December 25, 2018 - made several passes over Korolev crater in 2017, taking image strips with its DSLR High-Resolution Stereo Camera (HRSC).
According to Science Alert, five of those strips were stitched together to create the stunning collage, showing the crater in its full glory, at a resolution of about 21 meters (69 feet) per pixel.
They were also used to create a color-coded topographic map (above), which shows the elevations of the crater and surrounding plain.
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