The evolution of the albedo of dark spots observed on Mars polar region

► We present a methodology to remove atmospheric effects from HiRISE images. ► We study the time evolution of the albedo of dark spots observed in Richardson Crater, on Mars south polar region. ► Our results support the gas venting hypothesis previously proposed to explain the formation of dark spots. ► We propose that, once dark spots form, liquid brine formation can temporarily drive their evolution.