Spider-like channels appear on the surface of Mars, captured by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter. Ten thousand citizen scientists have helped NASA scientists zoom in on regions containing these features. Image credit: NASA/JPL-Caltech/Univ. of Arizona


Citizen scientists have been working to help NASA identify surface features in the Martian south polar regions known as ‘spiders’.

The features consist of multiple channels that converge, making them look like a spider’s legs.

Scientists had previously confirmed the features to be caused by thawing ice warmed by the ground below.

Frozen carbon dioxide thaws and builds up as a gas, escaping through the cracks and pulling dust with it, carving the spider-like vents.

The latest study of these icy cracks involves not just NASA scientists, but ten thousand volunteers working from home.

Looking at images from the Context Camera (CTX) on NASA's Mars Reconnaissance Orbiter (MRO), the citizen scientists were able to identify different seasonal terrains on Mars near the planet’s south pole using the Planet Four: Terrains website.

The volunteers identified over 20 regions that are now being investigated in higher resolutions using the MRO’s High Resolution Imaging Science Experiment (HiRISE) camera.

"The trapped carbon dioxide gas that carves the spiders in the ground also breaks through the thawing ice sheet," says planetary scientist Meg Schwamb, of the Gemini Observatory in Hawaii.

"It lofts dust and dirt that local winds then sculpt into hundreds of thousands of dark fans that are observed from orbit.

For the past decade, HiRISE has been monitoring this process on other parts of the south pole.

The 20 new regions have been added to this seasonal monitoring campaign.

Without the efforts of the public, we wouldn't be able to see how these regions evolve over the spring and summer compared with other regions."

New observations of the areas pinpointed by the volunteers have already shown that some of the spiders occur in areas where the surface consists of material ejected by impact craters that has covered up an older surface.

"Crater ejecta blankets are erodible. Perhaps on surfaces that are more erodable, relative to other surfaces, slab ice would not need to be present as long, or as thick, for spiders to form," says HiRISE Deputy Principal Investigator Candice Hansen of the Planetary Science Institute.


"We have new findings, and new questions to answer, thanks to all the help from volunteers."