Solar thermal propulsion

Solar thermal propulsion is a form of space craft propulsion. Space craft propulsion is used to change the velocity of space craft and artificial satellites. There are many methods for space craft propulsion. Each method has draw backs and advantages, and space craft propulsion is an active area of research. Solar thermal propulsion conceived in 1956 by Kraft Echrike. Solar thermal propulsion is an excellent choice because it requires only one propellant gas and combines moderate thrust with moderate propellant efficiency. Solar thermal propulsion effectively bridges the performance gap between chemicals and electric propulsion by potentially offering higher specific impulse (800 to 1000 seconds) than chemical propulsion (300 to 500 seconds). Typically hydrogen is used as the propellant due to its low molecular weight corresponding to a high specific impulse.

A solar thermal rocket has to carry only the means of capturing solar energy such as concentrators and mirrors. Instead of converging solar energy to electric power as like a photovoltaic system, a solar thermal propulsion system uses the solar energy directly as heat. The heated propellant is fed through a conventional rocket nozzle to produce thrust. The engine thrust is directly related to the surface area of the solar collector and to the local intensity of the solar radiation.