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Commercial Space Operations Noise and Sonic Boom Measurements 3 Summary As the frequency of commercial space operations and number of licensed launch sites in the United States continue to grow rapidly, accurately assessing the impacts of propulsion noise and sonic booms on surrounding communities will become even more critical. Historically, efforts to quantify and predict community noise impacts have been impeded by inadequate availability of well-documented, high-fidelity data. Furthermore, no comprehensive standard for obtaining acoustic data from space transportation operations currently exists. Therefore, the aim of this research project was to develop a well-documented, high-fidelity database of acoustic measurements acquired using a consistent data collection and analysis protocol. Ultimately, the acoustic database developed during this effort will enable future researchers to validate and enhance the models used to predict community noise exposure from space transportation activities. First, a survey of historical measurements was performed to assess the availability, quality, and limitations of existing acoustic datasets in relation to the objectives of this research effort. The existing datasets identified in the literature survey spanned from the historic Apollo era to the present Space Launch System (SLS) development. All existing full-scale propulsion noise and sonic boom measurements were assigned into groups of high, moderate, and low levels of data quality based on criteria associated with the acoustic data acquisition system, measurement sites, measurement methods, data analysis, documentation, and potential uses. Datasets with well-documented, high-fidelity acoustic measurements and supporting operational and meteorological data (i.e., vehicle trajectory data and weather conditions) were classified as high quality. Unfortunately, none of the surveyed datasets within the existing body of literature were classified as high quality in all acoustic, operational, and meteorological categories. Nevertheless, the existing datasets were compiled into a database, in which all files were archived in their native formats to preserve the content of the original sources. Insights gathered from the literature review were leveraged to develop a community noise measurement protocol that defines measurement methods and documentation procedures for obtaining accurate, reliable, and repeatable noise data for commercial space operations. Furthermore, the protocol was revised and improved based on experience acquired during the measurement campaign. The resulting community noise measurement protocol specifies requirements for acquisition systems to obtain dependable acoustic, operational, and meteorological data. The protocol also provides guidance for measurement site layouts applicable to a wide range of acoustic events, vehicles, and operation types that occur in space transportation scenarios. Additionally, data analysis and documentation procedures for both propulsion noise and sonic boom events are defined in the protocol. The noise measurement, analysis, and documentation techniques described in the protocol ensure that commercial space vehicle noise data are collected in a consistent manner. Reliable and repeatable measurements will provide confidence in the resulting community noise exposure predictions and ensure that data are useful for future model validation efforts. The community noise measurement protocol was applied during measurements conducted under this effort to develop a well-documented, high-fidelity database of acoustic measurements for commercial space operations. A measurement campaign was conducted between November 2017 and April 2019 to collect acoustic, operational, and meteorological data during the launches of the Antares 230, Falcon 9,
Commercial Space Operations Noise and Sonic Boom Measurements 4 Delta IV Heavy, and Falcon Heavy vehicles. These events represented a range of mission and operation types, including cargo resupply missions to the International Space Station (OA-8E and CRS-15), a research mission (Parker Solar Probe), a communications satellite launch (Arabsat-6A), and first stage return-to- landing operations (Arabsat-6A). Additionally, the measured launch vehicles possess mass-to-orbit capabilities ranging from medium to super-heavy lift designations. In total, over the four measured events, more than 250 acoustic recordings were collected from 70 sites at distances between 0.2 km and 27 km from the launch and landing pads at two distinct spaceports. The acoustic recordings include propulsion noise measurements from all four launch events as well as sonic boom measurements from the return- to-landing operations. The combined acoustic, operational, and meteorological data were analyzed and compiled into a publicly accessible database with thorough supporting documentation. The well-documented, high-fidelity propulsion noise and sonic boom measurement database developed during this research effort will equip future researchers with the information necessary to validate current noise models, identify shortcomings, and improve model accuracy by way of better propulsion noise and sonic boom source characterizations. Additionally, the comprehensive community noise measurement protocol will ensure that future measurement campaigns produce accurate, reliable, and repeatable noise data for evolving types of launch vehicles and operations; in the future, the protocol may even serve as a framework for a normative standard. Ultimately, the acoustic database and measurement protocol developed during this research effort will result in improved noise predictions, which will enable decision makers to provide more accurate information to the public regarding the potential community noise impacts from commercial space operations.
