Use of Model Payload for Europa Mission development IEEE aerospace conference

During the long early development of the Europa Mission concept, the team used a hypothetical, straw-man payload, called the Model Payload, to assist in the development of a complete mission design. The Model Payload comprised a suite of science instruments, and was structured to meet the science objectives of the mission. The science objectives were defined in terms of a set of specific physical measurements that would need to be made, including quality attributes such as resolution, accuracy, coverage, etc. The Model Payload was designed to acquire these data with the required attributes. A set of notional instruments was chosen to be able to meet the full set of science objectives. Each notional instrument was based on current capabilities and technologies of actual, similar instruments, and modeled with enough detail to be able to estimate aspects of the instrument such as power usage, pointing stability needs, thermal accommodation needs, etc. This paper discusses the basis for the Model Payload and how it was used to develop the mission design, observation and data acquisition strategy, needed spacecraft capabilities, spacecraft-payload interface needs, mission system requirements, and operational scenarios. Then we present a comparison of the Model Payload to the actual payload, recently selected by NASA for the proposed Europa Mission. The focus is on how well this process enveloped and constrained the design space and guided the development and analysis of not only instrument requirements, but also those of the flight system and the mission operations system. Specifically, we discuss those areas in which the Selected Payload drove the mission design and which areas remained unchanged. Lastly, we present lessons learned from the use of a Model Payload.