COST CONSIDERATIONS FOR INTERSTELLAR MISSIONS

This paper examines the technical and economic feasibility of interste llar exploration. Three candidate interstellar propulsion systems are evaluated with respect to technical viability and compared on an estim ated cost basis. Two of the systems, the laser-propelled lightsail (LP L) and the particle-beam propelled magsail (PBPM), appear to be techni cally feasible and capable supporting one-way probes to nearby star sy stems within the lifetime of the principal investigators, if enough en ergy is available. The third propulsion system, the antimatter rocket, requires additional proof of concept demonstrations before its feasib ility can be evaluated. Computer simulations of the acceleration and d eceleration interactions of LPL and PBPM were completed and spacecraft configurations optimized for minimum energy usage are noted. The opti mum LPL transfers about ten percent of the laser beam energy into kine tic energy of the spacecraft while the optimum PBPM transfers about th irty percent. Since particle beam generators are roughly twice as ener gy efficient as large lasers, the PBPM propulsion system requires roug hly one-sixth the busbar electrical energy a LPL system would require to launch an identical payload. The total beam energy requirement for an interstellar probe mission is roughly 10(20) joules, which would re quire the complete fissioning of one thousand tons of Uranium assuming thirty-five percent powerplant efficiency. This is roughly equivalent to a recurring cost per flight of 3.0 Billion dollars in reactor grad e enriched uranium using today's prices. Therefore, interstellar fligh t is an expensive proposition, but not unaffordable, if the nonrecurri ng costs of building the powerplant can be minimized.