Trade-off study of green technologies for upper stage applications

As an emerging trend, Green Propulsion has been exponentially growing over the last decades in the space sector. This paper assesses different technologies in a trade-off study weighting their applicability to a specific class of upper stage systems currently developed by many companies and often referred to as kick-stages or orbital stages. In a generic two-stage-to-orbit scenario, many launchers require a system able to go the ‘extra mile’ to deliver one or multiple payloads on orbit(s). That is where the kick stage comes into playing a crucial role. The trade-off study reported here is based on a well known decision-making tool, the Analytical Hierarchy Process, and is divided into two parts: low-thrust class engines such as monopropellants, including pre-mixed blends, usually employed for attitude and reaction control; and high-thrust engines such as hypergolic bi-propellants combinations used for apogee manoeuvres. Hybrid thrusters are also considered in the analysis with a dedicated parallel trade-off.