Preliminary Propulsion System Design for an expandable Cargo Spacecraft for LEO Customer Stations

Abstract

In this study, the propellant combinations MON/MMH and HTP/ethanol were compared and weighed against each other in three categories: performance, safety and availability. On the basis of an initial draft of a propulsion system for the new cargo spacecraft "Little SUSIE", an optimised propulsion system should be preliminarily designed. The result of the propellant comparison, based on a rather subjective weighting, was that MON/MMH was slightly better than HTP/ethanol, proving this green propellant combination as a serious competitor against hydrazine-based propulsion, though. For the design optimisation of the propulsion system, MON/MMH was still considered as the baseline. The most notable improvement is the reduction of required attitude control thrusters from 26 to 16 by improving the thruster allocation while still retaining a redundancy of two. This reduces mass, cost, and refurbishing efforts.