The Spiral North Pole of Mars
			
		
		
		
			Why is there a spiral around the North Pole of Mars? 
Each winter 
this pole 
develops a new outer layer about one meter thick composed of 
carbon dioxide frozen out of the thin Martian atmosphere. 
This fresh layer is deposited on a water-ice layer that exists year round. 
Strong 
winds blow down 
from above the cap's center and swirl due to the spin of 
the red planet -- 
contributing to 
Planum Boreum's spiral structure. 
The featured image is a perspective mosaic generated earlier this year from numerous images taken by ESA's Mars Express and elevations extracted from the 
laser altimeter aboard NASA's 
Mars Global Surveyor mission. 
New missions to Mars planned in the next few years include 
Insight 
with plans to drill into Mars, and 
ExoMars 
and the 
Mars 2020 Rover 
with plans to 
search for signs of microscopic Martian life -- past and present.