While the presence of liquid water on Mars remains an ongoing topic interest, we know that there is plenty of water ice on the planet.
The European Space Agency on Thursday released an image taken by its Mars Express mission, showing the Korolev crater filled with water ice.
Like Earth, Mars does have seasons. And like Earth, the warmer seasons result in receding ice. But 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’s a type of geological feature known as a ‘cold trap’, and that’s exactly what it sounds like. The floor of the crater is very deep, just over 2 kilometres below the rim. From the floor of the crater rises a dome of water ice, 1.8 km thick and up to 60 km in diameter.
In volume, it contains around 2,200 cubic kilometres of ice.
When air travels over the ice (yes, Mars has air – it’s unbreathable and thin, but it’s there), it cools and sinks, resulting in a layer of cold air that sits directly above the ice. Since air is a poor conductor of heat, this cold layer acts as an insulator that protects the ice from warmer air, and therefore keeping it from melting.
The same dynamic is at play in the much smaller 36-kilometre Louth crater, also in the northern polar region of Mars.