The ROARS (Revealing Orbital and Atmospheric Responses to Solar activity) swarm will provide a disruptive step-change to knowledge of our upper atmosphere with direct impacts to fundamental science, space weather forecasting and satellite conjunctions warnings. This report describes a prephase A feasibility study into the mission concept. This study formulates the scientific requirements, investigates the payloads and outlines the developmental pathways to meet the requirements. The analysis includes design of the spacecraft and full mission, including launch, orbital insertion and formation maintenance, to provide the envisaged distributed set of scientific measurements of magnetosphere-ionosphere-thermosphere interactions and associated effects on satellite orbits.