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The Socrates experimental vehicle is part of ESA’s Future Launchers Preparatory Programme (FLPP). Its purpose is testing under realistic conditions of a number of flight and ground operations typical for a reusable launcher. ESA’s ESTEC Concurrent Design Facility carried out an assessment study for such a vehicle, with the objective to analyze a few vehicle options, perform a preliminary design, identify the critical issues and to define overall performance and costs. Two options were studied furthering more detail. The first is an aircraft-like, vertical take-off vehicle with a LOX/LH2 propulsion system. The second option is similar, but uses a LOX/Kerosene propulsion system. Each vehicle can fly up to about Mach 5 without boosters, and reach Mach 10 or higher with the help of a single Castor IVB booster. Flights at relatively low Mach numbers can be performed at the existing Kourou launch base acting as both launch and landing site. Fights at the highest required velocities need separate launch and landing locations, for which the combination Esrange and Svalbard is proposed. In a comparison of life-cycle costs versus performance, the LOX/Kerosene-based vehicle was found to be the most optimal choice, under the condition that the requirement of demonstrating LOX/LH2 operations can be given up.