Mars still holds the promise of being one of the first places in the solar system humanity will colonize. However, if there was evolutionarily distinct, extant life on the planet, it might sway the heart of even the most ardent Mars colonization fans. So astrobiologists are in a race against time to try to determine whether or not such life exists, before the entire planet becomes an analog of Earth’s biosphere, if only unintentionally, and only a shadow of the ones that exist here.