The purpose of this study is to evaluate the different concepts and identify the advantages for telecom bi-propellant systems. The study should trade-off component (pump types) as well as assessing the impact of the propulsion system as a whole.

The current state of the art for bi-propellant propulsion systems employed by telecom spacecraft is to have a gas regulated system to maintain the propellant feed pressure in the propellant tanks for the Apogee engine burn. For on-station the pressure in the propellant tank is allowed to decay over life (aka blowdown) and thus the thruster propellant inlet pressure (and hence thruster performance) decays over time. Recently a number of different pump concepts have been proposed to improve the performance of propulsion launcher systems. The idea is to investigate the potential of introducing pumps of this type to replace the gas pressurisation system to supply the correct propellant feed pressure to the thrusters. This would have two major advantages - Firstly to replace expensive and complicated equipment (ie gas regulators) as well as reducing the cost of propellants tanks as they would no longer be required to operate at a high pressure. The second advantage is that potentially the feed pressure can be maintained at a constant rate over the entire duration of the mission and thus eliminating the need for a blowdown mode and hence reduction in thruster performance over life. The output of this activity would be as follows: - Assess the current state of the art and proposed concepts of propulsion pumps - Assess the impact (pro's and con's) on the propulsion system of introducing pumps , the assessment should cover technical aspects/impacts to the propulsion subsystem well as other platform subsystems i.e. thermal, structural, electrical. In addition any cost impact should also be assessed. - Downselection to a new pump candidate technology. - Produce a technology, cost and schedule development roadmap for the downselected technology,