Swirling spirals at the north pole of Mars
A new mosaic from ESA's Mars Express shows off the Red Planet's north polar ice cap and its distinctive dark spiralling troughs.
|Perspective view of Mars north polar ice cap [Credit: ESA/DLR/FU Berlin; NASA MGS MOLA Science Team]|
The ice cap is a permanent fixture, but in the winter season – as it is now in early 2017 – temperatures are cold enough for around 30 percent of the carbon dioxide in the planet's atmosphere to precipitate onto the cap, adding a seasonal layer up to a metre thick.
|Mars north polar ice cap in context [Credit: NASA MGS MOLA Science Team]|
Strong winds are thought to have played an important role in shaping the ice cap over time, blowing from the elevated centre towards its lower edges and twisted by the same Coriolis force that causes hurricanes to spiral on Earth.
|Colour mosaic of Mars north polar ice cap [Credit: European Space Agency]|
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.
|Perspective view of Chasma Boreale [Credit: ESA/DLR/FU Berlin; NASA MGS MOLA Science Team]|
This presents a valuable record for the nature of how the planet's climate has changed as its tilt and orbit varied over hundreds of thousands of years.
Source: European Space Agency [February 03, 2017]