Call for public to study Mars images

image captionAn image of the Martian surface showing fan-shaped deposits which reflect the wind conditions at the time they were deposited

Members of the public are being asked to help identify dust features on the surface of Mars.

Volunteers can go to the Planetfour website to see millions of images taken by the Mars Reconnaissance Orbiter (MRO).

The images show some unusual features around Mars' southern polar region.

The website gives volunteers a quick tutorial which illustrates some of the likely features of the Martian Antarctic.

They are then asked to explore the images and record any unusual activity.

Every winter Mars' southern polar region is blanketed by a layer of frozen carbon dioxide (dry ice), up to one metre deep. In the springtime, this seasonal polar cap sublimes (changes directly from ice to gas).

"One of the things we found in the MRO images is a really weird set of features that are associated with this process," says Chris Lintott from Oxford University.

image captionThis image shows fans with 'spiders' or 'araneiform' - channels which have built up around a fan

Over the winter the seasonal ice layer is transformed to translucent slab ice, which allows sunlight to penetrate to the ground below in the spring. The ground warms up causing the ice to sublime from the bottom.

This results in gas becoming trapped below the ice layer, under increasing pressure. When a crack or a rupture develops the gas flows out of the opening. The escaping gas carries along loose material, or dust, eroded from the ground. The gas and dust flow up to the top of the ice layer and out into the ambient wind.

The material lands on top of the seasonal ice layer, downwind of the vent, in fan-shaped deposits.

Weather snapshot

"Every Spring we get a network of really quite spectacular geysers of gas suddenly ripping up from underneath the surface. What you see from orbit is a deposit of material in a fan shape that is left over from the explosion. Over time channels build up around this and those channels tend to be known as 'spiders'", adds Dr Lintott.

They have these long, thin legs all coming from a central point. What we'd like to do is to try and understand this process because it will help us understand the dynamics of the Martian atmosphere and Martian weather."

But these spiders and fans can only be found by eye - there's no computer that can pick them out, and they change over time.

Planetary scientists want to identify the regions where these explosions are happening and make a weather map of the last few years, by using the fans to trace the wind directions.

"We want people to look through images of the Martian surface - it's a region that's never been explored in this detail before - no one has ever seen these images close up, so we don't know what would be there," says Dr Lintott.

"When you're exploring new territory you always expect the unexpected, this is a very un-Earth like place, so we don't really know what might or might not be there.

In other MRO images people have spontaneously found avalanches happening, for example.

We've also got a shot at finding some fresh craters, from impacts just in the few years while MRO has been in orbit. This is uncharted territory."

Dr Candice Hansen, one of the scientists working on the project, cautions that "there won't be instant results - we will take the citizen scientist measurements of the fans and turn them into maps of wind direction over time. We'll then compare existing Mars weather models to our data."

Contributors can check the Zooniverse website to keep up to date with the project's progress.

Stargazing Live returns to BBC Two at 20:00 GMT on Tuesday, Wednesday and Thursday, 8-10 January 2013. Preliminary results of the Mars exploration by Stargazing viewers will feature in the final programme.

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