Architectural Options and Optimization of Suborbital Space Tourism Vehicles

Since the creation of the Ansari X-Prize, a significant technical and commercial interest has developed in suborbital space tourism. An obvious question arises: what system architecture will provide the best combination of cost and safety for the performance defined by the prize? The objective of this paper is to address this question, by defining the design space and searching comprehensively through it with respect to launch mass (a proxy for cost) and safety. We have identified 33 architectures and visualized them in a single table. Of these, 26 have not earlier been proposed. A genetic algorithm optimized each of these 33 architectures for launch mass and safety. The launch mass was calculated by a design framework consisting of four modules: weight/size, propulsion, aerodynamics, and trajectory. To calculate the safety, a quantitative risk analysis is then developed. It is based on a hazard list with associated severities and likelihood factors. For each architectural feature, a mitigation factor is defined which quantifies the mitigation potential of an option during the design phase for a certain hazard. For a four-participant vehicle, six non-dominated architectures could be identified that merit a more refined design analysis.