Stunning Mosaic of Mars’ North Pole Ice Cap

Researchers, using a camera aboard ESA’s Mars Express, have created a stunning mosaic of Mars’ north polar region.

Perspective view of Mars’ north polar ice cap and its distinctive dark troughs forming a spiral-like pattern. The view is based on images taken by ESA’s Mars Express and generated using elevation data from the Mars Orbiter Laser Altimeter on board NASA’s Mars Global Surveyor. Image credit: ESA / DLR / FU Berlin / NASA / MGS / MOLA Science Team.

This mosaic shows the extraordinary, almost perfectly symmetrical pattern of Mars’ north polar ice cap, 684 miles (1,100 km) in diameter.

The mosaic was generated from 32 individual orbit ‘strips’ captured between 2004 and 2010 by the High Resolution Stereo Camera (HRSC) onboard the Mars Express spacecraft.

According to planetary researchers, Mars’ north polar cap is geologically young and is composed of a mixture of water ice and frozen carbon dioxide, the main element of Mars’ atmosphere.

The ice cap covers an area of around 386,000 sq. miles (one million sq. km), and has a volume equivalent to almost half the size of the Greenland ice sheet on Earth.

It has a persistent water-ice cap about 1.2 miles (2 km) deep, with an additional thin layer of carbon dioxide ice in cold winter months.

Temperatures fall to below minus 193 degrees Fahrenheit (minus 125 degrees Celsius) during the Martian winter, which is twice as long as Earth’s due to Mars’ two-year orbital period and is characterised by long polar nights due to the tilt of its rotational axis.

During the warmer summer months most of the carbon dioxide ice turns directly into gas and escapes into the atmosphere, leaving behind the water-ice layers.

Strong Martian winds are thought to have played an important role in shaping the ice cap over time, blowing from the elevated center towards its lower edges and twisted by the same Coriolis force that causes hurricanes to spiral on Earth.

Mars’ north polar ice cap. The position of the north pole is marked. Image credit: ESA / DLR / FU Berlin / CC BY-SA 3.0 IGO.

Mars’ north polar ice cap. The position of the north pole is marked. Image credit: ESA / DLR / FU Berlin / CC BY-SA 3.0 IGO.

One particularly prominent feature is a 311 mile- (500 km) long, 1.2 mile- (2 km) deep trench that almost cuts the cap in two.

The plunging canyon, known as Chasma Boreale, is thought to be a relatively old feature, forming before the ice-dust spiral features, and seemingly growing deeper as new ice deposits built up around it.

Layers that, in a similar way to tree rings, reflect the seasonal changes in ice accumulation and dust coverage due to Martian storms can be seen at its steep slopes.

By examining these layer sections, researchers hope to obtain information about the development of the Martian climate.

Why Chasma Boreale was cut into the ice cap of the north pole at this precise location through the forces of erosion is not clear. The canyon could have formed due to prevailing wind directions or by a gigantic outflow of a lake beneath the ice cap.

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