Trending in Probability of Collision Measurements

A simple model is proposed to predict the behavior of Probabilities of Collision (P(sub c)) for conjunction events. The model attempts to predict the location and magnitude of the peak P(sub c) value for an event by assuming the progression of P(sub c) values can be modeled to first order by a downward-opening parabola. To incorporate prior information from a large database of past conjunctions, the Bayes paradigm is utilized; and the operating characteristics of the model are established through a large simulation study. Though the model is simple, it performs well in predicting the temporal location of the peak (P(sub c)) and thus shows promise as a decision aid in operational conjunction assessment risk analysis

Preface

This publication has been financed by the Faculty of Mathematics and Computer Scienc

In situ scanning electron microscopy indentation studies on multilayer nitride films: Methodology and deformation mechanisms

Systematic studies of the deformation mechanisms of multilayer transition metal nitride coatings TiN/CrN, TiN/NbN, and NbN/CrN, and corresponding reference coatings of TiN, NbN, and CrN deposited by a direct current (dc) magnetron sputtering process onto silicon 〈100〉 have been performed. Mechanical characterization was conducted using a combination of microindentation and nanoindentation in the load range 30 to 150 mN and 0.5 to 3.5 mN, respectively. For both load ranges, scanning electron microscopy (SEM) in situ indentation was used to observe the indentation process including any pileup, sink-in, and fracture mechanisms specific to each coating. The coatings' microstructure, both before and after indentation, was analyzed using transmission electron microscopy (TEM). It was possible to both correlate the indentation load-displacement response to surface roughness effects and fracture modes (substrate and film cracking) and observe deformation mechanisms within the coating

Peak Pc Prediction in Conjunction Analysis: Conjunction Assessment Risk Analysis

Satellite conjunction risk typically evaluated through the probability of collision (Pc). Considers both conjunction geometry and uncertainties in both state estimates. Conjunction events initially discovered through Joint Space Operations Center (JSpOC) screenings, usually seven days before Time of Closest Approach (TCA). However, JSpOC continues to track objects and issue conjunction updates. Changes in state estimate and reduced propagation time cause Pc to change as event develops. These changes a combination of potentially predictable development and unpredictable changes in state estimate covariance. Operationally useful datum: the peak Pc. If it can reasonably be inferred that the peak Pc value has passed, then risk assessment can be conducted against this peak value. If this value is below remediation level, then event intensity can be relaxed. Can the peak Pc location be reasonably predicted

Launch COLA Operations: An Examination of Data Products, Procedures, and Thresholds

NASA GSFC and KSC, acting in response to headquarters NASA direction, performed a year-long study of launch collision avoidance (LCOLA) operations in order to determine and recommend best risk assessment and mitigation practices. The following condenses the findings and recommendations of the study into one short summary, a more expanded version of which appears as Section 10

Permanent grasslands in Europe : Land use change and intensification decrease their multifunctionality

Acknowledgments We acknowledge the financial support of this work by European Union Horizon 2020 research and innovation programme, under grant agreement 774124, project SUPER-G (Developing Sustainable Permanent Grassland Systems and Policies).Peer reviewedPublisher PD