DIORAMA as a System Simulation and Modeling Tool

Abstract

The Distributed Infrastructure Offering Real-time Access to Modeling and Analysis (DIORAMA) codebase is a software framework developed to support the United States Space Nuclear Detonation Detection (SNDD) program by providing system level modeling and simulation capabilities. It offers a broad set of packages able to simulate the physics of neutron, x-ray, gamma-ray, optical, and EMP phenomenologies from emission (generic or nuclear), to propagation through the atmosphere, and sensing onboard current or future satellite constellations. Communication between satellites and downlinks to ground stations as well as analysis algorithms based on received signals are also modeled. Some examples of simulation functionality include space vehicle reliability, calculation of integrated radiation dose to the space vehicle, the impact of payload changes on system performance, and global coverage calculations. Strict adherence to latest industry standards on code development ensure that the framework provides a robust capability to instrument designers, system modelers, and decision makers. A test driven design workflow in conjunction with continuous integration testing facilitates the development performed by a diverse group of scientists and engineers. A key component to DIORAMA models is the verification, validation, and accreditation (VV&A) process that each release goes through with input from multiple external government organizations and federally funded research and development centers. The nominal workflow for using DIORAMA consists of generating an XML scenario file in which a satellite constellation is described along with its associated sensors and event definition. Satellite constellations may be arbitrarily large and can be designated by static positions or time dependent two-line elements, with their onboard sensors ranging from simple line of sight determinations up through high-fidelity physics models that record energy deposition and sensor response. Events may be a simulated nuclear explosion or a generic emission that specifics time and energy dependence of one or more of the phenomenologies listed above. A user friendly, web-based GUI is also provided for easy access to the tools. For the highest level of flexibility user defined sensor/propagation models and analysis algorithms can be developed then linked against DIORAMA libraries to take advantage of already accredited tools. Because DIORAMA can be used to predict the performance of operational and future systems it is available at a variety of classification levels (OUO//ECI through TS//SCI) in order to guard restricted information. Releases are currently provided as precompiled libraries via the RedHat Package Manager (RPM) system as well as in the form of virtual machines for easy distribution and setup.