The DarkNESS CubeSat will deploy skipper-CCDs, the most sensitive silicon detectors to date, on a nano-satellite to study the diffuse X-ray background in the Milky Way and search for Dark Matter (DM). DM is an abundant, but invisible, presence in our Universe. It dictates how galaxies were initially formed and influences their dynamics today. The total mass of DM in the universe is known to be five times that of ordinary matter, but its true nature remains elusive, and its identity is one of the biggest questions in science today. We will search for DM by mapping the Galaxy's diffuse X-ray spectrum using an array of skipper-CCDs on a nanosatellite in LEO. This will address the experimental conundrum associated with the observation of an unidentified 3.5~keV X-ray line, potentially produced from the decay of a DM particle. The mission will also perform a direct search for low-mass, strongly-interacting DM candidate particles that would not penetrate the Earth's atmosphere and are therefore inaccessible to terrestrial DM experiments

DarkNESS CubeSat: development of Skipper CCDs for X-ray astronomy