Innovation: Using Solid Oxide Electrolysis, EVE enables balloon exploration of Venus with unlimited duration by replenishing the initial buoyant gas with CO and O2 from the ambient CO2 derived using Solid Oxide Electrolysis (SOE) . CO and O2 can also be used for power during the ~50 hr night-time traverse or to provide rocket propulsion. The innovation also enables large mobile future platforms capable of providing compressed fuel and oxygen to a fleet of airborne explorers. Impact: The Venusian atmosphere is the most habitable place in the solar system outside Earth yet, compared to Mars, it is relatively unexplored. Using in situ resources, EVE will enable thorough investigation of the surface and atmosphere, including sample return. What we learn from Venus will inform our understanding of climate change on our own planet. Approach: In NIAC Phase I we will model all aspects of SOE performance, experimentally verify 75% CO2 conversion and regenerative power production, identify a materials approach to tolerating SOx, flesh out the system design for the representative mission, and evaluate advanced capabilities including mobility, surface sample recovery, and return-to-space. Representative Mission: Our representative mission focuses on demonstrating longevity with SOE-derived replenishment while performing landmark science. Capabilities to be highlighted include the use of gases generated on the day-side traverse to provide electrical power on the night-side.