External Pulsed Plasma Propulsion for Interstellar Probes

We propose to evaluate external pulsed plasma propulsion for unmanned interstellar exploration. The concept rests on three quantitative observations: (1) the ORION concept is capable of achieving exceedingly-high specific impulse; (2) the unfueled weight of the spacecraft is greatly reduced by eliminating the springs and shock absorbers, originally intended to mitigate g-loading on astronauts, but less necessary for the rugged instrumentation packages alone; and (3) the external plasma pulse spacecraft could be staged to attain velocities that would permit it to cross interstellar space on humanly compatible time scales.The technical objectives are: (1) to assess the pusher-plate, spring, and shock absorber technology for appropriate trade-offs between impulsive g-loading and the total unfueled weight of the spacecraft; (2) to assess the gain in specific impulse achievable with directed energy pulse units; (3) to explore the limits and trade-offs of staging as a means to achieve exceedingly high velocities; (4) to calculate realistic scenarios for interstellar missions, including the relative resource requirements and relative costs; and (5) to objectively compare the merits of external pulsed plasma propulsion for interstellar probes with other means of propulsion, such as, ion beam beams, fission fragment ejection, Earth-based laser ablation, Earth-based microwave radiation-pressure, etc.