Novel Observing Strategies Testbed: A Lightweight, Collaborative Platform for Prototyping Earth Observing Missions

Abstract Distributed space mission concept development increasingly relies on collaborative, software-based testbeds, yet established distributed simulation standards and mission-operations frameworks impose overhead disproportionate to early-stage prototyping. Operating the first version of the Novel Observing Strategies Testbed exposed five systemic limitations---identity and authorization, reliable and persistent messaging, session resilience, schema governance, and coordinated scenario time control---that hindered long-duration, multi-institutional use. We evolved the testbed across two further versions to address them: Version 2 hardened the identity, messaging, session, and schema layers, and Version 3 added coordinated scenario time control through programmatic freeze, resume, and time-scale orchestration, while keeping the platform lightweight, cloud-native, and standards-aligned. Two independent Snow Observing Strategy campaigns, spanning 577 scenario days and closing the loop with an external land-surface model, validated the evolved architecture at technology readiness level 6. The campaigns delivered zero message loss, automated session recovery, sub-second coordinated freezes, and event-driven resume that eliminated idle waiting, and they coordinated a multi-sensor observation-selection workflow toward improving snow water equivalent estimation. The testbed thereby offers an accessible, standards-aligned platform for evaluating novel observing strategies before costly development, generalizable well beyond the snow domain.