Swirling spirals on the red planet have been spotted by European Space Agency’s Mars Express. The orbiter has sent back images revealing distinctive dark spiralling troughs on the north polar ice cap of Mars.
A mosaic has been created using 32 individual orbit strips that were clicked between 2004 and 2010. The strips cover an area of around a million square kilometres.
Though the ice cap on Mars is a permanent fixture, but during winters, the temperatures are cold enough are cold enough for around 30 per cent of the carbon dioxide in the planet’s atmosphere to precipitate onto the cap. This adds a seasonal layer up to a metre thick.
In summers, however, most of the carbon dioxide ice turns directly into gas. It then leaves behind the water-ice layers and escaped into the atmosphere.
It has been believed that strong winds have played an important role in shaping up the ice cap over time. They blew from the elevated centre towards its lower edges and twisted by the same Coriolis force that causes hurricanes to spiral on Earth.
One particularly prominent feature is a 500 kilometre-long, two kilometre-deep trench that almost cuts the cap in two.
The plunging canyon is also known as Chasma Boreale. It 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.
Radar instruments onboard Mars Express and NASA’s Mars Reconnaissance Orbiter conducted subsurface investigations. They revealed that many individual layers of ice and dust extending to a depth of around two kilometres formed the ice cap.
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.
(With inputs from PTI)