Enceladus’s long-lived plume of ice grains and water vapor makes accessing oceanic material readily achievable from orbit (around Saturn or Enceladus) and from the moon’s surface. In preparation for the National Academies of Sciences, Engineering and Medicine 2023–2032 Planetary Science and Astrobiology Decadal Survey, we investigated four architectures capable of collecting and analyzing plume material from orbit and/or on the surface to address the most pressing questions at Enceladus: Is the subsurface ocean inhabited? Why, or why not? Trades specific to these four architectures were studied to allow an evaluation of the science return with respect to investment. The team found that Orbilander, a mission concept that would first orbit and then land on Enceladus, represented the best balance. Orbilander was thus studied at a higher fidelity, including a more detailed science operations plan during both orbital and landed phases, landing site characterization and selection analyses, and landing procedures. The Orbilander mission concept demonstrates that scientifically compelling but resource-conscious Flagship-class missions can be executed in the next decade to search for life at Enceladus.

土卫二长期存在的冰粒和水蒸气羽流使得从轨道（围绕土星或土卫二）和月球表面很容易获得海洋物质。为准备美国国家科学院、工程院和医学院 2023-2032 年行星科学和天体生物学十年调查，我们调查了四种能够从轨道和/或地表收集和分析羽流物质的架构，以解决土卫二最紧迫的问题：地下海洋有人居住吗？为什么或者为什么不？研究了特定于这四种架构的交易，以评估与投资相关的科学回报。该团队发现，Orbilander 是一种首先绕轨道运行然后降落在土卫二上的任务概念，代表了最佳平衡。因此，Orbilander 被以更高的保真度进行了研究，包括在轨道和着陆阶段更详细的科学运营计划、着陆点特征和选择分析以及着陆程序。Orbilander 任务概念表明，在未来十年内可以执行具有科学意义但具有资源意识的旗舰级任务，以在土卫二寻找生命。