Ganymede Archives

(Top) Measured OC albedo values from Goldstone (from Table 4) and (bottom) measured OC albedo values from the GBT (from Table 5). The horizontal dashed lines indicate the weighted means of the albedos, which is 0.90 for Goldstone and 0.80 for GBT. The error bars on our albedo values are taken to be the total uncertainty calculated in Section 4. The color bar on the right shows the dates of our observations in YYMMDD. The x-axis is the subradar point west longitude. -- [astro-ph.EP]

Radar Observations Of Europa in 2011-2024: New Insights Into Radar Scattering Properties

by Keith CowingAugust 20, 2026August 20, 2026

[astro-ph.EP] Three of Jupiter’s Galilean satellites – Europa, Ganymede, and Callisto – are of particular scientific interest due to their icy shells and suspected subsurface oceans. However, the radar properties […]

Jupiter

Joint Dynamical-geophysical Evidence For A Limit Cycle In The Galilean Moons

by Keith CowingAugust 7, 2026August 7, 2026

[astro-ph.EP] Io, Europa, and Ganymede orbit in the Laplace mean-motion resonance, where their orbital and thermochemical evolution are strongly coupled [1-5]. Forced eccentricities sustain tidal dissipation, powering Io’s volcanism and […]

The north polar region of Jupiter’s volcanic moon Io was captured by NASA’s Juno during the spacecraft’s 57th close pass of the gas giant on Dec. 30, 2023. Data from that flyby and one on Feb. 3, 2024, is helping scientists understand Io’s interior. Image data: NASA/JPL-Caltech/SwRI/MSSS Image processing by Gerald Eichstädt

Lava World Recon: Juno Studies Io’s Volcanoes

by Keith CowingJuly 23, 2026July 23, 2026

[NASA] NASA’s Juno mission has provided the first measurements of the temperature below the surface of Jupiter’s moon Io, revealing significant heating within the shallow subsurface of the most volcanically […]

Ganymede and Callisto As Seen By Voyager -- NASA

Jupiter

The Recent Crossing Of The 7:3 Resonance Between Ganymede And Callisto

by Keith CowingJuly 10, 2026July 10, 2026

[astro-ph.EP] Io, Europa and Ganymede are locked in the well-known Laplace resonance, while Callisto is not, even though it is very close to the 7:3 mean motion resonance with Ganymede. […]

Illustration of key factors affecting subsurface ocean habitability and possible chemical evolution in icy moons Factors with question marks are still under debate. -- The Innovation via PubMed

Icy Worlds

Dynamic Controls On Subsurface Water Chemistry And Habitability On Icy Moons

by Keith CowingJune 23, 2026June 23, 2026

Icy moons are natural satellites whose surfaces contain a substantial fraction of frozen materials, most notably water ice.

This artist's impression shows radar waves from the NASA Goldstone Solar System Radar pinging one of Jupiter’s moons, Europa. The radar waves penetrate Europa’s icy surface before bouncing back to be collected by the NSF Green Bank Telescope on Earth. Credit: NSF/AUI/NSF NRAO/P.Vosteen

Callisto, Europa, Ganymede, Habitable Zones, Icy Worlds, Journal articles, Press Release, Water/Hycean Worlds & Oceanography

Radar Echoes From Europa Reveal Secrets Beneath the Ice

by Keith CowingJune 18, 2026June 18, 2026

A team of scientists has used NASA’s Goldstone Solar System Radar and the U.S. National Science Foundation Green Bank Telescope (NSF GBT) to carry out the most extensive radar study […]

Locations (yellow circles) of ROIs that include paterae, potential flows, and cryovolcanic candidate regions (K. Stephan et al. 2021a) on top of the global geological map of Ganymede from G. C. Collins et al. (2013). Mercator projection. -- The Planetary Science Journal

Astrogeology, Atmospheres, Climate, Weather, Biosignatures & Paleobiology, Ganymede, Habitable Zones, Icy Worlds, Imaging & Spectroscopy, Mapping, Geodesy, Cartography, Bathymetry, Missions & Hardware, Status Report

Potential Cryovolcanic Regions on Ganymede: A Priority Target for JUICE

by Keith CowingJune 7, 2026June 26, 2026

One of the Jupiter Icy Moons Explorer (JUICE) mission goals of the European Space Agency, launched in 2023 April, is the detailed characterization of Ganymede, Jupiter’s largest moon and a […]

Examples of materials with extremely high porosities (ϕ > 80%). a) Heesch & Laves (1933) 94.45% rigid packing structure. b) and c) pictures from Blum & Schr¨apler (2004) experiments of SiO2 agglomerates with 85% porosity. d) Water ice aggregates with 89% porosity observed with a long-distance microscope (Gundlach et al. 2011). Bottom Row: experimental pictures from the Core-Mantle Particle Sedimentation System e) Cryogenically cooled chamber with 15 mm high needles that serve as sample mounts for ice aggregates. f) Micrometer-sized water ice spheres as seen from the scanning electron microscope. g) Fractal ice aggregates as seen from the long distance microscope. Each individual grain has been highlighted in yellow on the right side of the picture. -- astro-ph.EP

Astrochemistry, Astrogeology, Icy Worlds, Imaging & Spectroscopy, Status Report

The Physical Nature of Regolith on Icy Moons

by Keith CowingMay 28, 2026May 28, 2026

Estimating surface properties such as porosity and grain sizes is key for planning lander missions and landing site selection on icy moons.

Astrogeology, Callisto, Ganymede, Icy Worlds, Imaging & Spectroscopy, Jupiter, Press Release

Ganymede Might Still Be Forming Its Metal Core Today

by Keith CowingMay 18, 2026May 18, 2026

Jupiter’s moon Ganymede is the largest moon in the solar system; at over 3,200 miles across, it is larger than the planet Mercury. It is also the only moon with […]

Numerical ocean-induction setup for Ganymede in a deep-ocean scenario with REM = 1.77 . Ganymede's internal structure is depicted, featuring the ice crust, the deep ocean with its simulated zonal flow, the internal ice layer, the silicate mantle, and the metallic core. Yellow tubes visualize the magnetic field lines. The bottom-right panel shows how magnetic field lines are sheared by the zonal (east–west) jet flow in the ocean (blue/red denote westward/eastward jets, respectively), thereby reflecting the secondary magnetic field induced by such dynamics. -- Geophysical Research Letters

Astrogeology, Biogeochemical Cycles & Geobiology, Ganymede, Icy Worlds, Jupiter, Magnetic Fields, Electromagnetism, bioelectricity,, Press Release, Water/Hycean Worlds & Oceanography

Motional Induction in Ganymede’s Ocean

by Keith CowingMay 10, 2026May 11, 2026

We investigate the magnetic signature of oceanic circulation in Ganymede’s subsurface ocean using kinematic induction modeling. Our approach couples zonal jet flows from rotating thermal convection simulations with magnetic field […]