Mars' 1000 km wide north polar ice cap showing off it's spiral structure. Image credit Nasa
27th May 2010
This is the northern ice cap of the cold desert world Mars, it contains mainly water ice together with frozen carbon dioxide (dry ice). But what you probably can’t help noticing though is the strange spiral structure of the ice that eminates from the centre. Looking almost like a spiral galaxy this pattern in the north polar cap was first spotted way back in 1972, and scientists have been wrestling with the mystery of just how it was formed ever since.
Right now Mars cannot do anything without our array of spacecraft or rovers (or should I say, rover) catching it in the act, or discovering something new. We have even photographed Martian avalanches as they happen, pretty amazing to think of when you see Mars as the little red dot in the night sky. Mars is rapidly becoming a well known and familiar place, and yet another mystery is no longer so. Scientists studying findings from the Nasa Mars Reconnaissance Orbiter have come up with an explantion to the ice cap’s unique look.
Using radar data from an instrument on board the spacecraft, a cross section of part of the ice cap has been constructed showing the individual layers of ice that have been laid down over the millenia.
In this image the thin layers can clearly be seen inside the main 1.2 mile thick section of the polar ice cap, together with the undulating crests and troughs that form the characteristic spiral patterns on the surface. But what has been discovered is that the Martian wind is the the natural force at work here, responsible for sculpting and shaping the spirals in the northern ice cap. Over the ages the wind has influenced the way the ice has grown, and even explains a huge chasm in the ice called the Chasma Boreale. You can see this canyon in the top photo, it’s the long dark formation at the right of the ice cap’s centre, at around the same length as Earth’s Grand Canyon but much deeper and wider.
Although Mars is smaller than our planet, the scale of some of it’s geography literally dwarfs anything we can boast about on Earth. What must it be like to stand at Mars’ north polar cap and see these colossal deep troughs in the ice that have been shaped by the winds?
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