Plume Particle Ejecta Can Trace Habitat-forming Gradients in Ocean Worlds: Insights from Planet Earth Geochemistry

Upcoming explorations for habitability in the ocean worlds of the solar system can greatly benefit from searching beyond parameters such as water, organics, nitrogen, phosphate, and silicate and being able to detect signs of metal catalysis.

As metabolism needs metal clusters and nanoparticles, detecting them, disentangling how they form, and linking them to the functioning of Earth’s analog habitats can help us explore the life-supporting processes in ocean worlds like Europa and Enceladus.

Here, we present theoretical insights on how nanoparticles in general, and metal-bearing nanoparticles in particular, with their known mechanisms of formation across pH, temperature, and redox gradients and their superior stability and transportability, can serve as a habitability tracer.

We outline an interdisciplinary oceanography-planetary science approach based on a case study of Earth analogs of pelagic and deep-sea hydrothermal redox gradients, as this is where the multi-element signatures of suspended marine nanoparticles began to emerge. This approach, incorporating new data sets from multiple sites under different gradients, will enable the linking of such “biogeosignatures” to their representative habitats.

This interdisciplinary direction will enhance the interpretations of elemental compositions of ocean world plume ejecta, anticipated to emerge from current space missions like Europa Clipper and JUICE.

Illustration of possible formation processes of nanoparticles on ocean worlds. Red circles indicate plumogenic nanoparticles. Yellow circles signify pelagic nanoparticles. Green circles are for hydrothermal fluxes. — The Planetary Science Journal

Evolution of ancient hydrothermal fluids theoretically inverted with initial oxygen isotopes of water, The Planetary Science Journal (open access)

Astrobiology,