Model-Based Assurance for Satellites with Commercial Parts in Radiation Environments

Small satellite projects often do not have the budget or schedule to incorporate radiation-hardened parts or extensive radiation test campaigns into their schedule. Yet a case must be made that the spacecraft will function as intended in orbit, with radiation, temperature and vacuum affecting part performance. The Vanderbilt Institute for Space and Defense Electronics, with support from NASA HQ, NASA NEPP, and NASA JPL, has developed a platform for making a safety case for systems with commercial (non-hardened) parts, called the Systems Engineering Assurance and Modeling (SEAM) platform. The platform has three elements: goal structuring notation (GSN), systems engineering models (SysML and our extensions), and Bayesian networks (BN). The GSN is a visual argument structure that presents an argument that the system meets specifications based on goals, strategies, and evidence. The systems engineering model is a high-level descriptive language that captures the spacecraft design and system architecture through various diagrams. We extend the SysML diagram set to include fault propagation diagrams, which map the environment, failure manifestations, anomalies, failure effects and responses (mitigation measures) of components and systems. The SEAM platform provides a low-cost alternative to conventional radiation hardening assurance paradigms

Using Pulsed Lasers as a Diagnostic Tool for Radiation-Induced Single-Event Latchup

Femtosecond pulsed lasers are a useful diagnostic and screening tool when evaluating electronic parts for potentially destructive radiation-induced single-event effects such as single-event latchup (SEL). Pulsed lasers may be used to estimate sensitive cross-sections and for comparing the relative sensitivity of equivalent parts

Global COVID-19 lockdown highlights humans as both threats and custodians of the environment

The global lockdown to mitigate COVID-19 pandemic health risks has altered human interactions with nature. Here, we report immediate impacts of changes in human activities on wildlife and environmental threats during the early lockdown months of 2020, based on 877 qualitative reports and 332 quantitative assessments from 89 different studies. Hundreds of reports of unusual species observations from around the world suggest that animals quickly responded to the reductions in human presence. However, negative effects of lockdown on conservation also emerged, as confinement resulted in some park officials being unable to perform conservation, restoration and enforcement tasks, resulting in local increases in illegal activities such as hunting. Overall, there is a complex mixture of positive and negative effects of the pandemic lockdown on nature, all of which have the potential to lead to cascading responses which in turn impact wildlife and nature conservation. While the net effect of the lockdown will need to be assessed over years as data becomes available and persistent effects emerge, immediate responses were detected across the world. Thus, initial qualitative and quantitative data arising from this serendipitous global quasi-experimental perturbation highlights the dual role that humans play in threatening and protecting species and ecosystems. Pathways to favorably tilt this delicate balance include reducing impacts and increasing conservation effectiveness