Solar thermal upper stages

Cost saving in future space transport systems has increased interest in new propulsion concepts for upper stages/orbital transfer vehicles, solar thermal propulsion (STP) in one of these concepts which, by reducing the propellant mass needed for orbit transfer can offer more payload than current chemical stages. The results presented here are mainly derived from an EADS study sponsored by ESTEC. A technological analysis of the main propulsion sub-systems is presented first and on this basis are predicted the performance improvement for some typical categories of launchers when their upper stage is replaced by a Solar Thermal Orbits Transfer System and with a 30 days transfer duration assumption.