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Commercial Space Vehicle Emissions Modeling 76 7 Emissions Modeling Tool Our team implemented the commercial space vehicle emissions model via a tool that enables practitioners to easily estimate the emissions from commercial space vehicle operations. The following sections describe the emissions modeling tool: ï Section 7.1 describes the limitations of existing software tools and the need for a dedicated tool to estimate commercial space vehicle emissions, and ï Section 7.2 presents RUMBLE 3.0, the launch vehicle noise and emissions simulation model developed by Blue Ridge Research and Consulting, LLC (BRRC). RUMBLE 3.0 and its accompanying user guide represent the primary products of this research. 7.1 Why is a Software Tool Needed? The spreadsheet emissions estimator tool presented in Section 6.4 is a simple implementation of the commercial space vehicle emissions model. However, the spreadsheet is intended as an example for future programmers and not as a general-purpose tool for practitioners. Since the spreadsheet was designed as an implementation example, it supports only one type of vehicle at a time. Additionally, it does not include an internal fleet database, so users must provide all required vehicle and engine parameters. A more capable tool is needed to provide the flexibility and ease-of-use for practitioners to estimate the emissions from scenarios involving multiple commercial space operations. AEDT is the standard tool for modeling emissions and noise from commercial aviation in the United States. As discussed in Section 6, the commercial space vehicle emissions model is designed with the intent to be integrated with AEDT. AEDT integration will result in a comprehensive suite of software tools for assessing the environmental impacts of both aircraft and spacecraft. However, AEDT integration is a multi-step process that may not be completed for many years. In the interim, a standard tool for estimating the emissions from commercial space vehicles is needed to enable practitioners to analyze the environmental impacts of the rapidly growing commercial space industry. 7.2 RUMBLE 3.0 To address the immediate need for a tool to estimate the emissions from commercial space vehicles, our team integrated the commercial space vehicle emissions model into RUMBLE, a launch vehicle acoustic simulation model developed by BRRC and expanded under ACRP project 02-66 . The resulting software tool, RUMBLE 3.0, is the first publically available tool that enables practitioners to accurately model the noise and emissions produced by commercial space vehicles.
Commercial Space Vehicle Emissions Modeling 77 Our team also developed a more than 100-page user guide  to accompany RUMBLE 3.0. The user guide provides the following detailed information: ï Installation instructions, ï Instructions on how to interact with RUMBLE 3.0, ï Descriptions of the input and output files, ï Example cases and tutorial exercises, ï Common error and warning messages, ï Technical details of the noise and emissions modeling methodologies, and ï The RUMBLE Standard Input File (RSIF) format reference guide. RUMBLE 3.0 is designed to be the standard tool for conducting environmental analyses of commercial space vehicles until the emissions model is fully implemented in AEDT. RUMBLE 3.0 implements the rocket noise and emissions models via a user-friendly interface, as shown in Figure 40. The user interface adopts a similar workflow as AEDT. As described in the user guide, users can create a study, add a spaceport, define operations, create scenarios, and calculate noise and emissions metrics. For example, Figure 41 shows the operations tab, which enables users to specify the type and number of operations, select a vehicle from the internal fleet database, and provide detailed trajectory data. Figure 40. Preview of the RUMBLE 3.0 user interface.
Commercial Space Vehicle Emissions Modeling 78 Figure 41. Preview of the RUMBLE 3.0 operations tab. The internal fleet database in RUMBLE 3.0 contains the engine performance parameters and primary emissions indices for many commercial space vehicles. Users can also add new space vehicles to the fleet database. Additionally, RUMBLE 3.0 includes example trajectories for horizontal and vertical launch vehicles and enables users to define custom trajectories. RUMBLE 3.0 uses the inputs from the internal fleet database and user-specified operational data to estimate the final emissions indices and calculate the emissions inventory and propellant burn report. RUMBLE 3.0 displays the calculated emissions inventory and propellant burn report in the emissions report viewer shown in Figure 42. The emissions report viewer enables users to group the results by different reporting options adopted from AEDT, sort the table columns, and change the units of the report. Additionally, users can easily export the results to a spreadsheet for further environmental analyses.
Commercial Space Vehicle Emissions Modeling 79 Figure 42. Preview of the RUMBLE 3.0 emissions report viewer. RUMBLE 3.0 and its accompanying user guide are freely available to the public through the ACRP website. RUMBLE 3.0 is a tool that enables practitioners to easily estimate the noise and emissions from commercial space operations. The comprehensive user guide provides installation instructions for RUMBLE 3.0, instructions for interacting with the user interface, descriptions of the input and output file formats, tutorial exercises, and technical details of the noise and emissions models. Together, RUMBLE 3.0 and its accompanying user guide fulfill the objectives of ACRP project 02-85.