Martian ‘spiders’ are a unique feature of the Red Planet that aren’t found on Earth and it seems that after years of waiting NASA scientists have finally been able to link together bits and pieces to determine how they are formed.
Mars missions have spotted these Martian ‘spiders’ – radially patterned channels – at the South Pole of Mars that range in size from tens to hundreds of meters; however, scientists haven’t been able to arrive at a consensus at how they come about and what is their initial starting point of formation. To find out how they are formed, scientists have been trying to detect year-on-year changes in these spiders through images captured by MRO’s High Resolution Imaging Science Experiment (HiRISE) camera but nothing that could provide concrete evidence of their formation and expansion came across.
Apparently it all starts with an erosion-carved trough that grow and branch during multiple Martian years. may be infant versions of larger Martian “spiders”. Carbon-dioxide ice, better known as “dry ice,” is found in the form of sheets that cover the ground during winter in areas near both poles, including the south-polar regions with spidery terrain. Dark fans appear in these areas each spring.
According to Hugh Kieffer of the Space Science Institute in Boulder in Spring the sunshine penetrates the ice to warm the ground underneath. This warming causes some carbon dioxide on the bottom of the sheet to thaw into gas. The trapped gas builds pressure until a crack forms in the ice sheet. Gas erupts out, and gas beneath the ice rushes toward the vent, picking up particles of sand and dust. This erodes the ground and also supplies the geyser with particles that fall back to the surface, downwind, and appear as the dark spring fans.
Scientists have now reported new troughs near the south pole which are also at spring-fan sites. They have not only persisted and grown through three Mars years so far, but they also formed branches as they extended. The branching pattern resembles the spidery terrain. Harder ground lies beneath the sand. Forming a spider may require ground soft enough to be carved, but not so loose that it refills the channels, as in the north. The new research sheds light on how carbon dioxide shapes Mars in unearthly ways including facilitating formation of the Martian ‘spiders’.