User Guides for Noise Modeling of Commercial Space Operations—RUMBLE and PCBoom (2018)

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1 This document includes user guides for the RUMBLE Version 2.0 Launch Vehicle Acoustic Simulation Model and the PCBoom Version 4.99 Sonic Boom Model for Space Operations. These user guides were developed along with a companion research report for ACRP Project 02-66, “Commercial Space Operations Noise and Sonic Boom Modeling and Analysis.” Published as ACRP Web-Only Document 33, it describes the development of two models to predict noise and sonic boom from commercial space operations from an environmental noise modeling perspec- tive. Commercial space operations are conducted to carry objects such as cargo, satellites, or pas- sengers, to, from, or in space, using orbital and suborbital vehicles owned and operated by private companies or organizations. These rocket-powered vehicles can generate significant noise and sonic boom levels that warrant environmental review of launch and reentry operations. The FAA Office of Commercial Space Transportation (AST) is responsible for analyzing the environmental impacts associated with proposed commercial launches and launch sites. AST regulates the U.S. commercial space transportation industry to ensure compliance with inter- national obligations of the United States, and to protect the public health and safety, safety of property, and national security and foreign policy interests of the United States (FAA 2014). An important part of this regulation is FAA issuance of vehicle and site operator licenses to conduct commercial space operations. Part of AST’s mission is to ensure that proposed commercial space operations comply with applicable environmental laws, regulations, and other requirements (AST Environmental Policy 2011). Pertaining to noise, this requires that suitable tools are avail- able for the evaluation of noise and sonic boom from these operations. Commercial space launch vehicle activities are expected to increase with growth in the num- ber of launch operators and in the emergence of different types of launch vehicles and missions designed to serve space tourism, satellite deployment, and International Space Station (ISS) cargo resupply. Figure 1 shows the current FAA-licensed launch sites as well as federal launch/ landing sites in the United States (FAA 2016). At present, many additional spaceport licenses are being considered. Table 1 lists the companies with active launch licenses. Launch vehicles are grouped into four basic types: (1) those that take off horizontally using jet engines with a rocket igniting after the vehicle is launched; (2) those that take-off horizontally under rocket power; (3) those that are attached to aircraft that take-off and are later released with a rocket igniting after release; and (4) those that take-off vertically. Each of these types of launch vehicles generate different noise and sonic boom impacts. These examples illustrate the complexity of the noise and sonic boom exposure generated by these space operations: Example #1: Vehicles in the third category above, which can be represented by Virgin Galactic’s White KnightTwo (WK2) and SpaceShipTwo (SS2), generate noise from both the aircraft take-off part of the mission (WK2) and the subsequent rocket-powered suborbital flight C h a p t e r 1 Introduction

2 User Guides for Noise Modeling of Commercial Space Operations—rUMBLe and pCBoom (SS2). SS2 is a reusable, winged spacecraft designed to carry as many as eight people into space (Virgin Galactic 2017). Sonic boom from this type of suborbital flight may occur on ascent as the rocket-powered vehicle reaches a high enough Mach number and pitches over; on descent sonic boom always occurs but overpressures are lower than on ascent, although small focal zones may develop and may be the dominant impact if they occur over populated areas. SS2 rocket engine noise occurs primarily during the ascent part of the suborbital flight which starts at approximately 50,000 feet mean sea level (MSL). Example #2: Another unique example of a commercial space operation that generates noise and sonic boom at multiple times during the operation is SpaceX’s launch of the Falcon 9 and recovery landing of its first stage. Figure 2 shows a graphic of the entire operation (launch, stage separation, and guided powered landing of the first stage). The Falcon 9 is a vertically launched rocket that generates engine noise during the launch and ascent phase (for example, from Kennedy Space Center). A sonic boom is then generated during the ascent phase, typically during and after the vehicle pitches over, and the resulting boom Figure 1. U.S. launch sites—spaceports. Company Vehicle Orbital ATK Minotaur IV Lockheed Martin Commercial Launch Services Atlas V Orbital ATK Minotaur-C Orbital ATK Pegasus Orbital ATK Antares Configuration 230 Space Exploration Technologies Corporation Falcon 9 Version 1.2 United Launch Alliance Atlas V-401 Virgin Galactic SpaceShipTwo Table 1. Active launch licenses.

Introduction 3 exposure occurs off coast in uninhabited areas. If SpaceX plans to recover the Falcon 9 first stage for reuse, then the first stage will generate a sonic boom during its reentry phase and the boom exposure will occur partly over land, with the highest boom levels occurring near the landing site. This is followed by the engine noise generated by the first stage during the landing phase of this operation. These two examples illustrate several different components of acoustic impact that occur during a single launch mission. They underscore the need to use rocket noise and sonic boom models during different phases of spaceflight and to predict the overall acoustic impact of a launch mission. The FAA has not yet designated an approved method for rocket noise analysis of commercial space operations. And, although there is an approved modeling method for sonic boom analysis of commercial space operations (FAA 2015), it is practiced by few and, until recently, did not include many of the current spacecraft as standard inputs. Developing rocket noise and sonic boom models that are considered standard for commercial space operations assessment will require that these models have approved modeling methodologies, include all current space- craft and operation types, have been validated in comparisons with field-measured acoustic data for spacecraft operations, have support for further development, and eventually have gained common use within the environmental planning community. Photo credit: SpaceX (Figure 2) Figure 2. Depiction of Falcon 9 first stage reusability.

4 User Guides for Noise Modeling of Commercial Space Operations—rUMBLe and pCBoom 1.1 About the RUMBLE User Guide RUMBLE 2.0, the rocket noise model developed by Blue Ridge Research and Consulting, LLC (BRRC) under ACRP Project 02-66, will be the first publicly available software tool designed to model commercial space launch, reentry, and static operations in space and time to com- pute far-field community noise exposure. The RUMBLE methodology has been approved for numerous environmental analyses of commercial space operations and it was the starting point for development efforts on this project. RUMBLE’s inputs, outputs, workflow, and graphic user interface (GUI) are designed to complement the FAA Aviation Environmental Design Tool (AEDT) and simplify future integration efforts. The RUMBLE user guide is organized into the following sections: • Chapter 2 introduces RUMBLE. • Chapter 3 presents the technical details of the methodologies employed by RUMBLE. • Chapter 4 provides detailed instructions on how to install and run RUMBLE. • Chapter 5 describes the noise metrics calculated by RUMBLE. • Chapter 6 defines the input files necessary to operate RUMBLE. • Chapter 7 provides instruction on how to interact with RUMBLE. • Chapter 8 describes the output files generated by RUMBLE. • Chapter 9 provides examples of the types of error and warning messages displayed in RUMBLE. • Chapter 10 presents examples and exercises to learn how to create study elements. • Chapter 11 provides guidance on the approval process when using RUMBLE to conduct environmental modeling for FAA actions subject to NEPA. • Chapter 12 describes the RUMBLE Standard Input File (RSIF) format and its usage. 1.2 About the PCBoom User Guide PCBoom 4.99, the sonic boom model developed under this project, is a single event, arbitrary maneuver, full-ray tracing model developed by Wyle, Inc. for more than 20 years. PCBoom is designed to analyze sonic booms from single flight operations. PCBoom4 (Plotkin et al. 2002) is the version used most often for sonic boom prediction of space vehicle operations and was recommended as the basis for the current project. The PCBoom user guide is organized into the following sections: • Chapter 13 introduces PCBoom. • Chapter 14 presents the technical details of the methodologies employed by PCBoom. • Chapter 15 provides detailed instructions on how to install and run PCBoom. • Chapter 16 defines the input files necessary to operate PCBoom. • Chapter 17 describes the sonic boom metrics calculated by PCBoom. • Chapter 18 describes the output files generated by PCBoom. • Chapter 19 provides a list of potential warnings and errors that might be encountered during a run. • Chapter 20 presents example cases, which take users step-by-step through the process of creating and running PCBoom for a vertical launch case and a suborbital flight case. • Chapter 21 provides instruction on PCBoom data display features and generating noise grids. • Chapter 22 provides instruction on how to generate sonic boom source signatures. • Chapter 23 provides guidance on the approval process when using PCBoom to conduct environmental modeling for FAA actions subject to NEPA.