An image from NASA’s Mars Reconnaissance Orbiter, acquired May 13, 2018 during winter at the South Pole of Mars, shows a carbon dioxide ice cap covering the region and as the sun returns in the spring, “spiders” begin to emerge from the landscape. Credit: NASA
Researchers at Trinity College Dublin have been shedding light on the enigmatic “spiders from Mars,” providing the first physical evidence that these unique features on the planet’s surface can be formed by the sublimation of CO2 ice.
Spiders, more formally referred to as araneiforms, are strange-looking negative topography radial systems of dendritic troughs; patterns that resemble branches of a tree or fork lightning. These features, which are not found on Earth, are believed to be carved into the Martian surface by dry ice changing directly from solid to gas (sublimating) in the spring. Unlike Earth, Mars’ atmosphere comprises mainly CO2 and as temperatures decrease in winter, this deposits onto the surface as CO2 frost and ice.
The Trinity team, along with colleagues at Durham University and the Open University, conducted a series of experiments funded by the Irish Research Council and Europlanet at the Open University Mars Simulation Chamber (pictured below), under Martian atmospheric pressure, in order to investigate whether patterns similar to Martian spiders could form by dry ice sublimation.
