This paper presents a low-cost microspacecraft platform concept for missions which require high ∆-v capabilities of up to about 1,500 m/s, using auxiliary launch opportunities, e.g., from the Ariane 5 ASAP. The proposed concept is extremely flexible and can be adapted to specific mission requirements, thus permitting low-cost missions to Earth orbit, as well as to the Moon, Mars, and selected asteroids. A particular focus of this paper is on the modularity of the proposed concept, including the bipropellant propulsion system needed to provide the required ∆-v, the lightweight structural concept, and the 3-axis attitude determination and control system (ADCS), as well as the available P/L masses and the most important spacecraft characteristics and constraints. The proposed microspacecraft platform is derived from the LunarSat concept, which has been developed by a team led by the Technische Universitat Munchen, Germany, and Surrey Satellite Technology Ltd., UK. Consequently, the LunarSat spacecraft and mission are presented as an example of the proposed concept.