Candice Hansen describes spidery channels on Mars

NASA scientists have taken close-up images from space of what they’re calling ‘spiders’ on the planet Mars. These spiders aren’t life forms, but spidery-looking channels, carved in ice at the south pole of Mars. That’s according to Candice Hansen of NASA’s Jet Propulsion Laboratory, who used images taken from the Mars Reconnaissance Orbiter to understand how these Martian spiders came to be.

Candice Hansen: This is a very interesting process, because there’s nothing like it on planet Earth. What you have is, over the winter, a layer of translucent ice forms. It’s carbon dioxide, so on Earth we would call that dry ice.

That’s the same dry ice you sometimes see at Halloween.

Candice Hansen: In the spring, sunlight penetrates through the translucent ice and it warms the surface below the ice. So it’s maybe half a meter of carbon dioxide ice that the sun has to go through. It warms the surface below. And then, as people who are familiar with dry ice on Halloween know, that ice will turn into a gas when it gets warm.

Hansen said that the gas below the layer of Martian ice is under pressure. So that gas looks for a weak spot to escape, such as a vent or a crack. As the gas shoots out, it carries along dust from the surface with it, which carves channels in the Martian surface as it gets blown up and out onto the top of the translucent ice.

Hansen said the closest thing on Earth to a Martian vent is Crystal Geyser in Utah, where bubbles of carbon dioxide drive the water to erupt.

Our thanks to:
Candice Hansen
Jet Propulsion Laboratory
Member of the HI-RISE Team,
Mars Reconnaissance Orbiter

March 12, 2008

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