Modularity Analysis for On-orbit Robotic Servicing of an Interferometer
- Paper number
IAC-07-A3.1.05
- Author
Ms. Swati Mohan, Massachussets Institute of Technology (MIT), United States
- Year
2007
- Abstract
The benefits of on-orbit servicing have clearly been demonstrated by the Hubble Space Telescope (HST). The implementation of modularity in the design allows HST to have instruments upgraded and failed components replaced; thus, it is kept on the cutting edge of technology. However, HST is a point modular design and cannot be easily generalized to other telescopes. Thus, it is necessary to develop a baseline modular design so future space telescopes can also benefit from servicing by easily incorporating modularity. Modularity is a key parameter in robotic servicing, as the characteristics of the modules drive the number and complexity of the servicing missions. This study develops a framework for comparing different modular designs and how they affect the servicing missions. The goal is to develop a tool for running trade studies to determine the impact of design parameters on the optimal design. An interferometer is specifically chosen for the initial study because the inherent modularity, due to the separated apertures. The tool presented here is developed to easily compare different architectures based on the following input parameters: type of interferometer, mission lifetime, number of apertures, level of modularity, and reason for servicing. The tool takes in the type of interferometer and first creates a topology map. The topology map is used to determine the highest level of modularity spatially imposed by the type of interferometer (formation flown versus structurally connected). Components are then assigned to these high level modules. The sub-module breakdown is computed from the components present in these high-level modules, the level of modularity desired, and the reason for servicing (ex. failure rate). Then, the tool employs a time simulation that steps through the length of the mission. It uses failure rate data to randomly fail components at different stages in the mission. When a part has “failed”, a servicing mission is planned based on the type of component that has failed, size/mass specifications of the failed part, and parts likely to fail soon. The number of servicing missions and their characteristics are totaled over the mission lifetime. Different architectures can then be compared using the following metrics: number, mass, and cost of servicing missions; overhead mass; number of modules; number of interfaces; and location of interfaces. Initial trade studies are conducted using this tool to determine if there is an optimum level of modularity for a given type of interferometer.
- Abstract document
- Manuscript document
IAC-07-A3.1.05.pdf (🔒 authorized access only).
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