Development of a Modular Solar Thermal Propulsion Engine

A new modular solar powered rocket engine is proposed to provide a few milligrams to a few kilograms of thrust at 900-1000 seconds of specific impulse by heating hydrogen propellant to average temperatures ranging from 2750 to 3250K. The proposed design utilizes one or several sunflower-like clusters of nonimaging concentrators coupled to optical fiber bundles that guide the solar energy with a throughput of greater than 80% into a Plank cavity/thrust chamber. The Plank cavity receives and entraps solar energy for direct heating of hydrogen and/or storage in a composite thermal storage unit. A nested flow path is designed to force hydrogen flow along the thermal storage/cavity temperature gradient, thereby, producing variable levels of thrust at relatively constant specific impulse of 900 to 1000 seconds. The innovative use of the sun tracking concentrators coupled to optical fibers, combined with the composite thermal storage unit/Plank cavity will allow for receiving and utilization of more than 80% of solar energy for producing thrust. This is a revolutionary improvement over existing solar-electric powered space propulsion systems and could lead to the development of an ultralight, compact, and an order of magnitude lower cost propulsion system for space transportation and solar system exploration.