The Expert Team on Earth Observing System Design and Evolution (ET-EOSDE) is tasked with designing and evolving the Earth Observing System under the WIGOS framework. It shapes policies and tools (like RRR and OSCAR), evaluates observing needs and capabilities, develops guidance documents to address capability gaps, conducts impact studies alongside modeling centers, and stewards the implementation of the longer-term Vision 2040 for observing systems.