Operational and Technical Updates to the Object Reentry Survival Analysis Tool

The Object Reentry Survival Analysis Tool (ORSAT) has been used in the NASA Orbital Debris Program Office for over 25 years to estimate risk due to uncontrolled reentry of spacecraft and rocket bodies. Development over the last 3 years has included: a major change to the treatment of carbon fiber- and glass fiber-reinforced plastics (CFRP and GFRP, respectively); an updated atmospheric model; a new model for computing casualty area around an impacting debris object; and a newly-implemented scheme to determine the breakup altitude of a reentry object. Software also was written to automatically perform parameter sweeps in ORSAT to allow for uncertainty quantification and sensitivity analysis for components with borderline demisability. These updates have improved the speed and fidelity of the reentry analysis performed using ORSAT, and have allowed for improved engineering understanding by estimating the uncertainty for each components survivability. A statistical model for initial conditions captures the latitude bias in population density, a large improvement over the previous inclination-based latitude-averaged models. A sample spacecraft has been analyzed with standard techniques using ORSAT 6.2.1 and again using all the updated models; we will demonstrate the variation in the total debris casualty area and overall expectation of casualty

Preliminary Characterization Results from the DebriSat Project

The DebriSat project is a continuing effort sponsored by NASA and DoD to update existing break-up models using data obtained from two separate hypervelocity impact tests used to simulate on-orbit collisions. To protect the fragments resulting from the impact tests, "soft-catch" arenas made of polyurethane foam panels were utilized. After each impact test, the test chamber was cleaned and debris resulting from the catastrophic demise of the test article were collected and shipped to the University of Florida for post-impact processing. The post-impact processing activities include collecting, characterizing, and cataloging of the fragments. Since the impact tests, a team of students has been working to characterize the fragments in terms of their mass, size, shape, color and material content. The focus of the 20 months since the impact tests has been on the collection of 2 millimeters- and larger fragments resulting from impact test on the 56 kilogram-representative LEO (Low Earth Orbit) satellite referred to as DebriSat. To date we have recovered in excess of 115,000 fragments, 30,000 more than the prediction of 85,000 fragments from the existing model. We continue to collect fragments but have transitioned to the characterization phase of the post-impact activities. Since the start of the characterization phase, the focus has been to utilize automation to (i) expedite fragment characterization process and (ii) minimize human-in-the- loop. We have developed and implemented such automated processes; e.g., we have automated the data entry process to reduce operator errors during transcription of the measurement data. However, at all steps of the process, there is human oversight to ensure the integrity of the data. Additionally, we have developed and implemented repeatability and reproducibility tests to ensure that the instrumentation used in the characterization process is accurate and properly calibrated. In this paper, the implemented processes are described and preliminary results presented. Additionally, lessons learned from the implemented automations and their impacts on the integrity of the results are discussed

Peri-urban Promises of Connectivity: Linking project-led polycentrism to the infrastructure scramble

This paper offers an interpretive framework linking polycentric urban expansion in emerging/frontier economies to the global extension of infrastructure networks. Drawing from scholarship on state restructuring, we theorize an infrastructure scramble whereby numerous state actors and agencies make massive investments in infrastructure connectivity to secure effective integration to transnational value chains as economic and geopolitical competition intensify. This has manifold territorial implications, and matters for debates on planetary urbanization. Novel urbanization processes include the proliferation of peri-urban nodes. Built in cheaply-available land, these respond to (or anticipate economic gains from) enhanced connective infrastructure. In contrast to city-regional exemplars, project-led polycentrism does not arise from territorially-decentralized governance arrangements, and may deepen peri-urban exclusion. The paper includes an experimental comparison of two peri-urban nodal projects: the Iranduba University City, located in a riparian rainforest of the Brazilian Amazon 17 miles from bustling Manaus, and the Bagamoyo Port and Special Economic Zone, located 35 miles north of the congested port of Dar es Salaam, Tanzania’s expansive capital. Our findings suggest that: i) techno-entrepreneurial capacity requirements underpin the centralist scalar politics governing the development of peri-urban nodes; as ii) state-led projects rely on ambitious physical planning, with masterplans evincing elite, globalization-oriented objectives that neglect local needs and trigger displacement; and iii) even failing projects spearhead varying trajectories of territorial transformation in erstwhile-stagnant peri-urban peripheries. Concluding, we call for further research on multiple drivers and modalities of polycentrism in the global South, and the infrastructure scramble’s broad implications for hyper-connected and bypassed territories