Mercury

Mercury is a mining world on the inner edge of the Sol System, close to the star Sol. Its proximity to the star was once offset by Cytheron generators dating from the Dark Age, which held Sol’s heat at bay.

During the Solar War, Alpha Legion cells employed the world’s scavenger clans. At a later date, the Adeptus Custodes and the Sisters of Silence destroyed a Genestealer cult on the Decima-Caldus platform before it could rise. Shoal habitats continue to operate in Mercury’s orbit.

Mercury’s record therefore combines resource extraction close to the star with two episodes of concealed activity: the Alpha Legion’s use of local clans during the Solar War, and the suppression of a Genestealer cult by the Custodes and the Sisters of Silence. The Shoal habitats in orbit indicate that the world remains inhabited and worked within the Sol System.