Spring on Mars: warmer weather and lots of gas

By Steve Connor, Science Editor

Tuesday, 31 March 2009



The Nasa images show deposits on the Martian floor and carbon dioxide 
sublimating from Mars' surface (above)

  a..  enlarge 

Spring on Earth is marked by daffodils and budding leaves. However spring on 
Mars sees plumes of carbon dioxide vaporising from solid blocks of dry ice as 
they warm up in the sunlight towards the end of the Martian winter.

The unearthly nature of a Martian spring has been captured by Nasa's Mars 
Reconnaissance Orbiter satellite as it circles the Red Planet taking images of 
dirty plumes of gas carrying dust from the ground up through the openings of 
the solid carbon dioxide layer covering the Martian poles.

The seasonal polar caps on Mars form each winter because carbon dioxide in the 
atmosphere changes directly to frost, which builds up into a thick layer of dry 
ice as much as a metre thick. 

As winter ends and spring arrives, the dry ice turns directly from solid into 
vapour which punches its way to the surface.

"Spring on Mars is quite different from spring on Earth because Mars has not 
just permanent ice caps, but also seasonal polar caps of carbon dioxide, 
familiar to us on Earth as dry ice," said Candice Hansen-Koharcheck, of Nasa's 
Jet Propulsion Laboratory in Pasadena, California.

"What happens on Mars, we think, is that as the seasonal ice cap thins from the 
bottom, gas underneath the cap builds up pressure. And where gas under the ice 
finds a weak spot or a crack, it will flow out of the opening, often carrying a 
little dust from the surface below," said Dr Hansen-Koharcheck.

Images from the High Resolution Imaging Experiment on board the satellite show 
how the dust patterns form into starburst patterns as they blow through the dry 

As the plumes of carbon dioxide emerge they form radial troughs called 
"spiders", so-called because of the way they look



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