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Mission Simulation and Analysis

Scope and Description

This topic covers simulation and analysis at the mission-level. It includes all high-level analyses used to complete conceptual orbit and mission architecture design and to determine subsystem-level requirements. This typically involves an interdisciplinary effort using commercial software tools that simultaneously simulate multiple, interconnected elements of the mission (e.g. orbit, targets, and ConOps) and custom-built spreadsheets or scripts for simpler modeling tasks. Modeling tools allow the conceptual design team to analyze the performance of candidate architectures and to finalize launch, ground segment, and subsystem-level spacecraft requirements.

Resources under this topic area are primarily software tools for mission analysis and articles and book sections that propose specific methodologies and guidance.

Best Practices and Lessons Learned

  • Mission-level simulation and analysis results should be evaluated against design requirements (with margin). For many requirements (e.g. mass, power generation) it is important that margins are larger during earlier phases of the design process. Chapter 3 of the NASA standard titled "Space Flight System Design and Environmental Test" provides various key mission and subsystem-level design parameter margins for different phases of the project lifecycle.
  • Before developing mission models, carefully consider and plan for the most efficient path forward. It can be tempting to develop excessively comprehensive and/or physically accurate models. Significant complexity and engineering effort can be saved by focusing the scope of mission models and reducing the required accuracy of each performance metric. This can be done by making well-reasoned assumptions and by requiring conservative design margins. The simplest example of this is to carefully identify and only analyze worst-case scenarios.

Resources

Software Tool
Jan King

This website provides Excel spreadsheet tools that can be used to carry out RF, link budget, mass budget, ... and power budget analyses for satellite missions. These spreadsheet models can be incorporated directly or adapted for integration into smallsat mission modeling workflows.

Software Tool
Analytical Graphics Incorporated

STK is a powerful tool for simulation and analysis of complex systems. This software tool can be used ... to effectively model several elements for a small satellite mission in a single simulation. The dynamics of ground vehicles, spacecraft, aircraft, and other objects can be integrated in these mission models. To build upon the capabilities of the baseline tool, various add-on modules are available from AGI. Many third party tools also exist for integration with STK.

Book
James R Wertz et al.

SMAD is a practical handbook for space mission engineering covering all aspects of a space system - from ... orbit and constellation design to operations. This reference is valuable as both an introductory text and a reference. This chapter covers identification of critical requirements, mission analysis, mission utility, and mission concept selection. While the mission analysis section provides valuable information, many of the references to commercial tools for mission analysis are outdated.

Software Tool
a.i. solutions

FreeFlyer is a commercial software tool for space mission design, analysis, and operations. Different ... versions are available for mission design and mission operations. The interfaces emphasize a robust scripting language. In general, this emphasis on scripting-based model development allows experts more control and visibility into the modeling but can make the tool more challenging for non-experts to learn and utilize.

Software Tool
NASA

GMAT is an open source software system for space mission design, optimization, and navigation. This tool ... can be used to model and simulate the operation of spacecraft subsystems and orbit and attitude dynamics. As a free and open source product, the ease of use, documentation, and support are somewhat limited relative to commercial solutions.

Software Tool
James R Wertz et al.

This web page contains links and downloads for figures and tables from the new edition of the Space Mission ... Analysis and Design (SMAD) book that the website is associated with. Spreadsheet models for a wide range of space mission modeling tasks are available for download. These spreadsheet models for payload performance, communications, orbit, and several other elements of a space mission can be incorporated directly or adapted for integration into smallsat mission modeling workflows.

Software Tool
George Sebestyen et al.

This web page provides spreadsheet tools for download. A number of these can be incorporated into mission ... modeling workflows. Among other things, these spreadsheets model orbital maneuvers, satellite ground imaging and downlink parameters, and space environment parameters. These tools are described in Chapter 21 of the book that they are associated with: Low Earth Orbit Satellite Design.

Article
Allan I. McInnes et al.

This conference paper describes a systems engineering tool for the high-level analysis of a smallsat ... design. The overall methodology and motivation for the prescribed assumptions and workflow are captured, and each high-level element of The Aerospace Corporation's SmallSatCEM spreadsheet-based model is described. While the technical details of the individual models are not covered, this is a useful resource for understanding the workflow and components of a comprehensive spacecraft-level model for systems engineering and conceptual design work.

This document defines engineering design and environmental test requirements and guidelines for NASA ... Class C and D space flight systems. This section is titled "Flight System Design" and covers both requirements and guidance. This is an excellent reference for setting baseline requirements and design margins on each element of a smallsat design. Margins are given at various key lifecycle milestones. The information is concise, practical, and references several other NASA and DoD documents in case additional detail is needed on a particular requirement or piece of guidance.

This appendix provides a smallsat mass budget document example.

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