With the creation of new citizen science website Planet Four, planetary scientists are turning to the general public for help in analyzing images of the surface of Mars, many of which have never been seen before. It's hoped that the public's input will help develop a detailed picture of winds on the planet.

The images were captured by the High Resolution Imaging Science Experiment (HiRISE) camera aboard NASA's Mars Reconnaissance Orbiter, and are limited to Mars' southern polar region (an effort to keep the workload manageable).

That task at hand is to identify and mark dark "fans" and "blotches," intriguing surface features the origin of which scientists can only speculate upon. The prevailing hypothesis is that, during the Martian autumn, a layer of carbon dioxide ice forms at the south pole. Come spring, sunlight penetrates the ice (which became translucent over the winter), heating the ground beneath it, causing the ice to sublimate (i.e. transform directly from solid to gas) from beneath. With gas accumulating at ever increasing pressure, and the ice sheet thinning from below, the ice inevitably cracks. When it does, gas erupts from the fissure like a geyser, taking loose surface material with it.

The resulting mark is dependent on the presence of wind. If there is a Martian breeze to blow the material in a certain direction a so-called fan will form with a clear point of origin. With no wind, the material falls directly back to Mars, creating a blob. In summer, the marks disappear completely.

Extending the hypothesis, it's thought that, over the course of Martian years, the process erodes shallow channels (less than 2 meters or 6.5 feet) in the Martian surface known as araneiform or spiders.

By selecting fan and blob tools from a menu, visitors to the Planet Four website can mark these features by clicking on the image presented. First up, I was lucky enough to be presented with the following image:

The idea is that every image will be presented to a number of visitors, and an aggregate of the information will be gathered that will eventually give a detailed picture of winds on Mars.

As well as marking fans and blobs, visitors are invited to flag interesting and unusual features they find. This transfers the image to a discussion section on the website, where scientists professional and amateur alike can attempt to explain them.

In the above image, which shows a bright blue (rather than dark) fan, Planet Four scientists believe that the escaping carbon dioxide gas has condensed back into frost on the surface of the ice.

Planet Four is a part of the Zooniverse family of citizen science websites. The site received a boost when it was featured, and some of its images discussed, on the BBC's Stargazing Live television show earlier this month. At the time of writing 56,033 volunteers have helped to classify 2,819,476 images. Jump in any time. You might just find something extraordinary.

Source: Planet Four

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