Where Exactly on Mars are the Terrains You’re Looking At?

With our new addition Planet Four: Terrains, we need your help to review CTX  (Context Camera) images and identify ‘spiders’ (radially organized channels carved in the surface), craters, pitted sheets of carbon dioxide ice nicknamed Swiss Cheese Terrain, and channel networks carved by carbon dioxide gas trapped below the thawing ice sheet and also by the freezing and thawing of water ice permafrost.

The CTX images are of the South Pole, but you might be wondering where exactly we’re looking. One of the main aims of Planet Four: Terrains is to identify new areas of interest to point HiRISE, the higher resolution camera on Mars Reconnaissance Orbiter. CTX is named the Context Camera because it provides the larger picture or context for HiRISE’s detailed but narrow image swaths. Anya’s gone in to more detail about this, so check out her blog to learn more.

To find new areas of interest,  for Planet Four: Terrains we wanted to extend beyond the regions we know have spiders because they’ve been imaged by HiRISE during the seasonal processes campaign. To give you some sense, here are  the regions targeted by HiRISE that are currently uploaded in the Planet Four database. This compromises  all imaged locations from Seasons 1,2,3 and Manhattan Season 4 and Inca City Season 4 and a small part of 5.

For picking the first set of CTX images, I went through and found what we think are ice free images from the end of Summer and early Fall, and selected as much of a random uniformly distributed sample south of -75 degree latitude. The reason we didn’t want ice if possible is that if there’s ice, there’s a chance for carbon dioxide  geysers and fans (the ones we ask you to mark on the original Planet Four). The fans would block you from seeing surface features in the ground below them.

Above are plotted the locations of the full frame CTX images used to make the  subframes that you see on Planet Four: Terrains (Note: we cut up the CTX images into 800 x 600, width x height,  pixel images). We currently have a random third of this set live on the site. We’ll be add the remaining subimages to the site over the next month or so.

For comparison, here again the previous HiRISE seasonal monitoring images locations uploaded on the original Planet Four, plotted on the same scale as the CTX plot above.

As you can see most of the HiRISE images from the seasonal monitoring campaign are focused south of -80 degrees. As you can see , we’re looking at much more of the Martian South Pole with Planet Four: Terrains.  Soon the South pole will be in darkness again, and the temporary carbon dioxide cap will start growing again. Our hope is that we can have these images reviewed before the start of the Spring on the South Pole to add new locations to the target list for Season 6 of the HiRISE monitoring campaign that starts around July 2016.

Check out Planet Four: Terrains, and classify an image or two today at http://terrains.planetfour.org