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Navigating the Deployment and Downlink Tradespace for Earth Imaging ConstellationsDistributed Spacecraft Missions (DSMs) are gaining momentum in their application to Earth Observation (EO) missions owing to their unique ability to increase observation sampling in spatial, spectral, angular and temporal dimensions simultaneously. DSM design includes a much larger number of variables than its monolithic counterpart, therefore, Model-Based Systems Engineering (MBSE) has been often used for preliminary mission concept designs, to understand the trade-offs and interdependencies among the variables. MBSE models are complex because the various objectives a DSM is expected to achieve are almost always conflicting, non-linear and rarely analytical. NASA Goddard Space Flight Center (GSFC) is developing a pre-Phase A tool called Tradespace Analysis Tool for Constellations (TAT-C) to initiate constellation mission design. The tool will allow users to explore the tradespace between various performance, cost and risk metrics (as a function of their science mission) and select Pareto optimal architectures that meet their requirements. This paper will describe the different types of constellations that TAT-C’s Tradespace Search Iterator is capable of enumerating (homogeneous Walker, heterogeneous Walker, precessing type, ad-hoc) and their impact on key performance metrics such as revisit statistics, time to global access and coverage. We will also discuss the ability to simulate phased deployment of the given constellations, as a function of launch availabilities and/or vehicle capability, and show the impact on performance. All performance metrics are calculated by the Data Reduction and Metric Computation module within TAT-C, which issues specific requests and processes results from the Orbit and Coverage module. Our TSI is also capable of generating tradespaces for downlinking imaging data from the constellation, based on permutations of available ground station networks - known (default) or customized (by the user). We will show the impact of changing ground station options for any given constellation, on data latency and required communication bandwidth, which in turn determines the responsiveness of the space system.
Document ID
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Nag, Sreeja
(Bay Area Environmental Research Inst. Petaluma, CA, United States)
Hughes, Steven P.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
LeMoigne, Jacqueline J.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
April 17, 2019
Publication Date
September 25, 2017
Subject Category
Spacecraft Design, Testing And Performance
Report/Patent Number
Meeting Information
Meeting: International Astronautical Congress (IAC)
Location: Adelaide
Country: Australia
Start Date: September 25, 2017
End Date: September 29, 2017
Sponsors: International Astronautical Federation
Funding Number(s)
Distribution Limits
Use by or on behalf of the US Gov. Permitted.
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