Europa Clipper: exploring Europa’s habitability

Introduction: With a launch readiness date of late 2024, NASA’s Europa Clipper will set out on a journey to explore the habitability of Jupiter’s moon Europa. In the early 2030s, the spacecraft will enter Jupiter orbit then fly by Europa nearly 50 times to collect data on Europa’s ice shell and ocean, study its composition, investigate its geology, and search for and characterize any current activity. The mission’s science objectives will be accomplished using a highly capable suite of remote-sensing and in-situ instruments.

Mission Context: Interpretation of Galileo mission data suggests that Europa likely hides a global saltwater ocean beneath the icy surface. Chemistry at the ice surface and ocean-rock interface might provide the building blocks for life. NASA’s Europa Clipper mission is intended to assess Europa’s potential habitability.

The Voyager and Galileo missions first revealed a deformed surface at Europa with an average surface age younger than Earth’s, dominated by water ice and renewed through recent or current geologic activity. Galileo data indicates that Europa has an induced magnetic field, implying the presence of a global, electrically conductive fluid layer beneath the surface, most likely a saltwater ocean. Geological data including structural patterns are also consistent with a subsurface ocean. Recent observations also suggest the presence of plumes may release internal water into space, indicating the potential for additional shallow water reservoirs beneath Europa’s icy surface.

There are many open questions regarding the viability of Europa to support life. Intense radiation from Jupiter at Europa’s surface forms water and impurities into oxidants, chemical reagents capable of carrying out oxidation. Active geologic cycling of seawater through rocky material on the Europan seafloor is expected to be chemically reducing. If mixing between the surface oxidants and the reduced ocean water occurs, there is an opportunity in Europa’s ocean or ice shell to produce a reduction-oxidation (redox) potential. All known life on Earth relies on such redox potentials to extract chemical energy from the environment in exchange for heat energy and entropy, enabling cellular maintenance, metabolism, and reproduction. Europa may have the ingredients that could support life: liquid water, bioessential elements, chemical energy, and a stable environment through time.

Science Goal and Objectives: The overarching goal of the Europa Clipper mission is to explore Europa to investigate its habitability. This will be achieved through the accomplishment of three science objectives:

• Characterize the ice shell and any subsurface water, including their heterogeneity, ocean properties, and the nature of surface-ice- exchange.
• Understand the habitability of Europa’s ocean through composition and chemistry.
• Understand the formation of surface features, including sites of recent or current activity, and characterize high science interest localities.

Science Payload: The remote sensing payload consists of the Europa Ultraviolet Spectrograph (Europa-UVS), the Europa Imaging System (EIS), the Mapping Imaging Spectrometer for Europa (MISE), the Europa Thermal Imaging System (E-THEMIS), and the Radar for Europa Assessment and Sounding: Ocean to Near-surface (REASON). The in-situ instruments comprise the Europa Clipper Magnetometer (ECM), the Plasma Instrument for Magnetic Sounding (PIMS), the SUrface Dust Analyzer (SUDA), and the MAss Spectrometer for Planetary Exploration (MASPEX). Gravity and Radio Science (G/RS) will be achieved using the spacecraft's telecommunication system, and valuable scientific data will be acquired by the spacecraft’s Radiation Monitoring system (RADMON).

Status and Advancement Toward Launch: Both the spacecraft and the payload are currently under construction, as the mission begins its assembly, testing, and launch operations (ATLO) phase. Recent major milestones include selection of a launch vehicle and launch readiness date by NASA, evaluation of candidate tours by the science team, and preparations for the cruise and operational phases of the mission. The project, flight system, and payload have completed their Critical Design Reviews, and the project has completed its System Integration Review. Europa Clipper is now formerly a Phase D mission. Meanwhile, the science team is preparing a set of manuscripts describing the mission’s science and instruments for publication in the journal Space Science Reviews.

One Team Philosophy: Our “One Team” philosophy prioritizes synergistic science by bridging across the individual instrument-based investigations, while promoting collaborations among members of the Europa Clipper science team. Each of the Europa Clipper individual instruments will be used to investigate Europa and its environs, finding critical clues about how Europa works as a planetary body. In combining and assessing the datasets from each instrument's experiments, we can collectively gain clarity into Europa’s mysteries. It is at the overlapping boundaries of our subfields that the greatest insights and discoveries will be made. Integrated science celebrates our individual expertise, challenges our assumptions, breaks through our limitations, and expands our intellectual boundaries. Associated visibility brings trust, promotes partnerships, and enhances personal relationships. These aspirations are the inherent basis for functioning as one Europa Clipper science team.

JUICE-Clipper Coordination: The JUICE spacecraft is expected to be in the Jovian system at the same time as Europa Clipper, and there is substantial overlap between these missions’ primary phases. The Europa Clipper and JUICE science teams have begun informal collaboration to suggest synergistic science that could be supported on a non-interference basis. The scientific collaborations currently extend across two ad hoc working groups, one on the Galilean satellites and one on Jupiter’s magnetosphere. Current discussions are to form a joint focus group to advise the two project teams on potential collaborations and   propose a plan for synergistic observations, joint publications, and joint archival data products.

Acknowledgments: Portions of this work were performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. This work was supported by NASA through the Europa Clipper Project.