Which bit of the Martian Arctic do you want to see first? As spring comes to this strangest of Martian landscapes, and as Planet Four participants wait to see a new season on fans appear, we’re teaming up with the HiRISE camera team to let you choose what to see first.

August 17, 2014 is the Northern Autumnal Equinox on Mars, signalling the beginning of Spring at the Red Planet's South Pole, and the start of the next season of monitoring of the region by the HiRISE camera aboard the Mars Reconnaissance Orbiter. The Sun will heat the carbon dioxide ice cap that formed over the South Pole during the winter, producing carbon dioxide jets. These jets carry dust and dirt from the ground below to the top of the ice sheet so that they can, we think, create the dark fans and blotches that are seen from orbit. Soon hundreds of thousands of these dark seasonal features will dot the ice sheet and be captured in HiRISE images. Here at Planet Four, we ask for your help in marking the sizes and positions of these features in order to better study the Martian climate.

Earlier this year Planet Four helped mapped three areas near Mars' South Pole: 'Inca City', 'Ithaca', and 'Manhattan'. To celebrate the equinox and the start of a new season of the HiRISE monitoring campaign, we're doing something special. In collaboration with the HiRISE team, we want you to decide which of these three areas will have its first Season 5 observation prepared for public release by the HiRISE team after it is taken. Perhaps there will already be fans, but who knows what we will see?

Vote for your favorite region below today. Voting will be open from August 1, 2014 9am GMT - September 1, 2014 9am GMT. We will be announcing the winning region on September 2nd, and in the meantime help us study the climate of Mars by mapping seasonal fans and blotches at http://www.planetfour.org


Inca City