Icy worlds

The geological similarities between icy and rocky worlds invite comparison and cross-fertilization of knowledge.

Pluto’s subsurface ocean and thickness variation in its ice shell may be maintained by a layer of methane clathrates forming an insulating cap to the ocean, according to calculations of thermal evolution and viscous relaxation.

Some lake basins in the polar regions of Titan may be craters from nitrogen vapour explosions due to past warming, according to analysis of their morphology in comparison to terrestrial explosion craters from magma–water interaction.

Ahuna Mons dome on Ceres formed by extrusion of a mixture of brine and solids sourced from a muddy mantle plume, according to numerical modelling of slurry rheology and a gravity anomaly found by the Dawn mission.

Domes on the dwarf planet Ceres could form by solid-state flow of low-density, ice-rich parts of its crust—a process analogous to salt doming on Earth—according to numerical simulations.

The large domes found on the dwarf planet Ceres may not result from cryovolcanism, but from solid-state flow analogous to salt doming on Earth, according to numerical simulations of gravitational loading.

Icy planets and moons could become habitable as their host stars brighten and their ice melts. Climate simulations instead show a rapid transition from a snowball to an inhospitable greenhouse climate with significant water loss.

The New Horizons mission has revealed Pluto and its moon Charon to be geologically active worlds. The familiar, yet exotic, landforms suggest that geologic processes operate similarly across the Solar System, even in its cold outer reaches.

The exploration of ocean worlds in the outer Solar System offers the opportunity to search for an independent origin of life, and also to advance our capabilities for exploring and understanding life in Earth’s oceans.

Sublimation rates of water ice in equatorial regions of Jupiter’s moon Europa are sufficient to sculpt bladed terrain that would pose a hazard to a potential lander mission.

The dwarf planet Ceres is thought to have an ice-rich layer in its shallow subsurface. The morphologies of craters, however, suggest little relaxation by viscous flow has occurred and instead indicate a subsurface that is less than 40% ice.

Despite evidence for an ice-rich outer shell, little water ice has been observed on the surface of Ceres. Lobate morphologies observed on Ceres that are increasingly prevalent towards the dwarf planet’s poles are consistent with ice-rich flows.

The dwarf planet Ceres may have reoriented in the past due to a heterogeneously dense crust, a scenario consistent with gravity and topographic data and the distribution of crustal fractures.

The shape and internal structure of bilobate comet 67P is controlled by shear deformation inducing mechanically driven erosion along shear fracture networks, according to a 3D analysis of images from the Rosetta mission.