Economic benefits of the use of non-toxic mono-propellants for spacecraft applications

The European Space Agency and other institutions have identified the use of non-toxic (or "green") propellants as a substantial cost saving opportunity in manufacturing and ground operating of spacecrafts. This paper attempts to identify and quantify this potential by replacing, in the near future, hydrazine, the current state-of-the-art propellant for small-to-medium size spacecrafts, with green mono-propellants. While most existing publications report results of specific propellant formulation development and testing at thruster and component level, this paper intends to quantify the cost reduction potential for satellite manufacturers arising from simplification of hardware and ground operations. The economic benefit potential of the use of non-toxic spacecraft mono-propellants is investigated by focussing on the four main cost driving parameters: · Reliability and safety, · Manufacturing, assembly, integration and test operations, · Launch preparation and support, · Ground support equipment and personal protection. Further, an extensive market analysis is presented where the currently available and investigated propellant formulations are screened and graded against defined selection criteria. Based on this grading a potential future mono-propellant is arrived at. The economic benefit of this specific propellant formulation is then quantified. The potential recurring cost saving for a 10 spacecraft constellation-type program is evaluated being in the order of € 2.5M, a sum which could provide a business case, also when considering one-off non-recurring costs for verification and validation of a propulsion system utilising green propellants. An outlook for the short and medium term is presented. It is argued that with reasonable expenses for hardware development and validation a demonstrator for the replacement of hydrazine may be feasible in the near future. Finally a "road map" for the long term is shown, where propellant formulations with higher performance characteristics than hydrazine may increase the utilization envelope for mono-propellant systems into the lower domain of bi-propellant propulsion. This could lead to a real "quantum-leap" in the efforts to pursue significantly lower satellite costs. © 2003 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.