Spooky 'spiders on Mars' finally explained after two decades - Space.com

played with a big chunk of dry ice to try to figure out what's behind the strange alien patterns known as the "spiders on Mars.".

Those patterns, visible in satellite images of the Red Planet's south pole, aren't real spiders, of course; but the branching, black shapes carved into the Martian surface look creepy enough that researchers dubbed them "araneiforms" (meaning "spider-like") after discovering the shapes more than two decades ago.

But in a new study published March 19 in the journal Scientific Reports, scientists successfully recreated a shrunken-down version of the spiders in their lab, using a slab of carbon dioxide ice (also called dry ice) and a machine that simulates the Martian atmosphere.

"This research presents the first set of empirical evidence for a surface process that is thought to modify the polar landscape on Mars," lead study author Lauren McKeown, a planetary scientist at the Open University in England, said in a statement.

In a 2003 study, researchers hypothesized that the spiders on Mars could form in spring, when sunlight penetrates the translucent layer of CO2 ice and heats the ground underneath.

But in the new study, researchers made a little slice of Mars here on Earth, using a device called the Open University Mars Simulation Chamber.

The team adjusted the chamber to mimic the atmospheric conditions of Mars, then slowly lowered the dry ice block onto the grains.

Regardless of the size of the sediment grains, the dry ice always sublimated on contact with them, and the escaping gas pushed upward, carving out spider leg-like cracks along the way.