Assessment of an Interstellar Photon Propulsion Concept

In the past decade, solar sail propulsion has been successfully demonstrated in space. In this paper, we propose a new type of interstellar propulsion system and critically examine its physical feasibility in the context of modern photovoltaic and solar sail technologies. This paper analyzes the viability of a spherical interstellar propulsion concept, and explores its physical parameters and the limitations against its practical implementation. The proposed system would use a spherical, thin film photovoltaic structure, relying on ambient light in the astrophysical environment for power and ultimately, thrust generation. Integrated diode lasers powered by the photovoltaic structure would produce a net unidirectional thrust in an adjustable direction with no onboard propellant. Compared to planar solar sails, there would seem to be inherent promise for niche applications where the distribution of radiant power sources is roughly isotropic, such as propulsion between stars or within a luminous nebula. However, our analysis indicates that the device is impractical as an interstellar propulsion system, primarily due to low thrust and long transit times that would exceed component lifetimes by orders of magnitude.