Exploration of Under-Ice Regions with Ocean Profiling Agents (EUROPA)

This report has identified the technology needs of a mission that will travel to Europa, penetrate its ice, and explore the ocean below. A plan for the mission including overviews of the required technologies and mission architectures was developed. This is based on an initial set of mission requirements that provides a list of everything that a mission to Europa should accomplish. A brief description of the Europan environment was provided for context of the mission. The phases of the mission, including discussion of existing enabling technologies and challenges, were enumerated to provide an understanding of how this mission will be completed. Prior missions to the outer planets are examined, which provide context and historical data for this mission. The proposed Europa "Clipper" mission is discussed, as it will provide essential knowledge for the planning of later missions to Europa. The science objectives of this mission are discussed. These objectives map the goals of the mission to achieve the driving need for an in-situ study of the Europan environment in the pursuit of habitable environments and/or extraterrestrial life. A value system is designed which is used to evaluate the design alternatives and potential mission architectures. This value system utilizes an analytical hierarchy process to compare design objectives. Current state-of-the-art technologies that will facilitate this mission are discussed. These technologies include underwater gliders, melt probes, and spacecraft power sources. The principals of operation and anticipated future developments for each of these technologies are outlined. Potential sensor packages for the hydrobot are discussed. Various design alternatives for the mission are outlined, and five potential mission architectures are carefully evaluated. The analysis within this report led to the selection of a final notional design for four vehicles, a lander, surface unit, cryobot, and hydrobot. The recommended mission architecture consists of three surface units, each carrying a cryobot, each of which transports three hydrobots through the ice to the ocean. The landing system is integral to each surface unit. The surface unit initiates the descent of the cryobot and buries radiation sensitive components in the tunnel left by the cryobot. Laser communication is used to maintain a communications link between the surface unit and one or more relay satellites, which transmit information back to Earth. The cryobot penetrates the ice using a RHU and maintains communication with the surface unit using a fiber optic tether and separate ice-embedded transceivers. Once the cryobot reaches the ocean, it embeds itself in the ice and releases the hydrobots. The hydrobots utilize a biomimetic propulsion mechanism that enables both swimming and gliding. Under-ice navigation techniques will utilize a combination of simultaneous localization and mapping and long base-line acoustic positioning supplementing ded reckoning. The hydrobots carry their sensors throughout the ocean, collecting valuable data about Europa and seeking markers of life or habitability. To communicate this data back to Earth, the hydrobots dock with the cryobot. While docked, the hydrobot recharges its battery energy storage system and, once recharged, returns to the ocean to make more discoveries.