Ganymede Archives

NASA image of Titan using the Cassini VIMS (visual and infrared mapping spectrometer) instrument. One impact crater is visible near the center. The dark areas near the equator are organic-rich sand dunes, and the dark areas in the north polar region are liquid methane/ethane lakes. White clouds are also visible in the northern hemisphere. -- Credit NASA/ Cassini VIMS

Astrogeology, Biogeochemical Cycles & Geobiology, Habitable Zones, Icy Worlds, Imaging & Spectroscopy, Mapping, Geodesy, Cartography, Bathymetry, Press Release, Saturn, Titan, Water/Hycean Worlds & Oceanography

Titan Has An Insulating Methane-rich Crust Up To Six Miles Thick

by Keith CowingNovember 25, 2024November 25, 2024

Saturn’s largest moon Titan is the only place other than Earth known to have an atmosphere and liquids in the form of rivers, lakes and seas on its surface. Because […]

A schematic diagram of the sulfur cycle on the icy Galilean moons. Not all processes operate on all moons and the circles with E, G, and C indicate which processes seem to be more restricted to Europa, Ganymede, and Callisto, respectively. Ice radiolysis happens on all icy surfaces and reactions of radiolytically produced H2SO4 can transform brine salts to sulfates. Only for Europa and Callisto the subsurface ocean is likely to be in contact with the rocky ocean floor but not for Ganymede, where massive dense ice layers prevents ongoing exchange of the subsurface with the silicates. The ocean compositions seem to be all quite similar in the beginning, and Ganymede’s ocean might be the oldest ur-ocean remaining since isolation by dense ice. Subsurface oceans on Europa and Callisto can evolve depending on silicate mantle outgassing into the oceans which may increase salinity over time. On Europa acidification from radiolytically produced H2SO4 may happen, which could lead to an ocean with compositional gradients and pH and development of a halocline. This diagram does not claim completeness and is an attempt to summarize observations, ideas and interpretations. -- astro-ph.EP

Astrochemistry, Astrogeology, Atmospheres, Climate, Weather, Biochemistry & Organic Chemistry, Biosignatures & Paleobiology, Enceladus, Europa, Ganymede, Gas Giants, Icy Worlds, Imaging & Spectroscopy, Io, Jupiter, Mapping, Geodesy, Cartography, Bathymetry, Neptune, Saturn, Status Report, Titan, Uranus

Sulfur in the Giant Planets, their Moons, and Extrasolar Gas Giant Planets

by Keith CowingOctober 18, 2024October 18, 2024

We review sulfur chemistry of the gas giant planets and their moons where sulfur compounds are observed. The major S-bearing gas in the upper atmospheres of the giant planets is […]

JUICE-Europa Clipper Tage Team exploration of Jovian Space -- ESA

Callisto, Europa, Ganymede, Habitable Zones, Icy Worlds, Jupiter, Water/Hycean Worlds & Oceanography

Astrobiology.com on Deutsche Welle: Europa Clipper and ESA Juice

by Keith CowingOctober 14, 2024October 15, 2024

Editor’s note: I was just on Deutsche Welle talking about the Europa Clipper mission – as well as ESA’s Juice mission – and how they will work in tandem exploring […]

The UVS instrument recorded spatial information produced by hydrogen atoms radiating from the Earth. In the background a number of individual stars are identified along with the Pleiades star cluster. Juice-UVS plans to similarly observe hydrogen atoms radiating from Ganymede and Jupiter’s other icy moons. Credit Southwest Research Institute

Callisto, Europa, Ganymede, Icy Worlds, Jupiter, Missions & Hardware, Press Release

Astrobiology Fleet Update: ESA Juice Tests SwRI Ultraviolet Spectrograph

by Keith CowingOctober 9, 2024October 9, 2024

As European Space Agency (ESA)’s Jupiter Icy Moons Explorer (Juice) spacecraft hurtled past the Moon and Earth in mid-August to provide its first gravity assist maneuver to the Jovian system, […]

This image, taken from a data visualization, shows Arctic sea ice minimum extent on September 11, 2024. The yellow boundary shows the minimum extent averaged over the 30-year period from 1981 to 2010. Download high-resolution video and images from NASA’s Scientific Visualization Studio: hhttps://svsdev.gsfc.nasa.gov/5382 NASA’s Scientific Visualization Studio/Trent L. Schindler

Analog Studies, Arctic / Antarctic / Alpine, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Cryobiology, Europa, Ganymede, Habitable Zones, Icy Worlds, Mapping, Geodesy, Cartography, Bathymetry, ROVs/Submersibles/Diving, Status Report, Water/Hycean Worlds & Oceanography

Ice Planet Update: Arctic Sea Ice Near Historic Low – Antarctic Ice Continues Decline

by Keith CowingSeptember 25, 2024September 25, 2024

Editor’s note: we live on a world that is mostly an ocean world, part Icy world, part desert world etc. Other worlds in our solar system exhibit both similar and […]

Above: Examples of typical surfaces of the icy Galilean satellites (panel a: Europa, near Conamara Chaos region at 8.1°N/90.9°E; panel b: Ganymede, Nicholson Regio at ∼14°S/12.7°E; panel c: Callisto, detail of Asgard impact basin at 14.7°N/218°E). All images are scaled to 150 m px−1. The crater density (a proxy of surface age) increases from Europa to Callisto, reflecting the geological history of surface processes. The surface of Europa displays the most complex inventory of landforms that were formed by endogenic processes, whereas Callisto’s surface is almost devoid of any evidence for tectonic and cryovolcanic activity (Image: NASA/DLR). Below: Models of the interiors of the icy Galilean satellites (Images: ESA/ATG Medialab). Details on their examination by JUICE are provided by Van Hoolst et al. (2024, this collection) -- pace Sci Rev via PubMed

Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Callisto, Europa, Ganymede, Habitable Zones, Icy Worlds, Imaging & Spectroscopy, Jupiter, Mapping, Geodesy, Cartography, Bathymetry, Missions & Hardware, Status Report

Characterization of the Surfaces and Near-Surface Atmospheres of Ganymede, Europa and Callisto by JUICE

by Keith CowingSeptember 17, 2024September 17, 2024

We present the state of the art on the study of surfaces and tenuous atmospheres of the icy Galilean satellites Ganymede, Europa and Callisto, from past and ongoing space exploration […]

Calibrated images of Ganymede’s 630.0 nm auroral emission displayed in 20 R contours. To better reveal the spatial variability we smoothed the data using a Gaussian kernel with a FWHM of 0. ′′5 approximating typical seeing conditions for the morning of 2021-06-08 UTC. The time in the upper left of each image is the UTC time at the start of the observation, the annotation in the lower right is the distance to the plasma sheet centrifugal equator; positive when Ganymede is above the mid-plane and negative when it is below. As Ganymede moved vertically through the plasma sheet, the hemisphere closest to the mid-plane exhibited the brightest aurora. From approximately 14:00 to 14:45 UTC, Ganymede is within ±0.5 RJ and the brightness is more evenly-distributed across the disk. Ganymede passed through the highestdensity plasma mid-plane at 14:20 UTC, so the top two rows display data when Ganymede was above the mid-plane (with enhanced brightness at southern latitudes) and the bottom row displays data when Ganymede was below the mid-plane (with enhanced brightness at northern latitudes). Because of the blurring effect of atmospheric seeing, the calibrated brightness distribution of the individual pixels is lower than the disk-averaged value reported in de Kleer et al. (2023) and table 1, which assume all emission originates from a disk with Ganymede’s solid-angular size. The white grid shows the physical size and orientation of Ganymede, with north pointing upward (for more details on this observing geometry, see figure 2). -- astro-ph.EP

Astrochemistry, Astrogeology, Atmospheres, Climate, Weather, Ganymede, Icy Worlds, Jupiter, Space Weather & Heliophysics, Status Report, Water/Hycean Worlds & Oceanography

Short-Timescale Spatial Variability of Ganymede’s Optical Aurora

by Keith CowingSeptember 11, 2024September 11, 2024

Ganymede’s aurora are the product of complex interactions between its intrinsic magnetosphere and the surrounding Jovian plasma environment and can be used to derive both atmospheric composition and density.

Kobe University HIRATA Naoyuki was the first to realize that the location of an asteroid impact on Jupiter’s moon Ganymede is almost precisely on the meridian farthest away from Jupiter. This implied that Ganymede had undergone a reorientation of its rotational axis and allowed Hirata to calculate what kind of impact could have caused this to happen.CREDIT HIRATA Naoyuki

Astrogeology, Comets and Asteroids, Ganymede, Icy Worlds, Impact events, Jupiter, Pluto, Press Release, Water/Hycean Worlds & Oceanography

A Gigantic Asteroid Impact Shifted The Axis Of Ganymede

by Keith CowingSeptember 4, 2024September 4, 2024

Around 4 billion years ago, an asteroid hit the Jupiter moon Ganymede. Now, a Kobe University researcher realized that the Solar System’s biggest moon’s axis has shifted as a result […]

A schematic configuration of PRIDE (not to scale) supporting two Jovian missions, JUICE (the lower left spacecraft) and Europa Clipper (the upper right spacecraft). The spacecraft are in two-way radio contact (blue arrows) with mission-specific Earth-based tracking stations (blue Earthbased antennas). Earth-based VLBI radio telescopes (three magenta Earth-based antennas) receive radio signals from the spacecraft (yellow arrows) and emission of distant natural celestial radio sources (red arrows). The configuration can operate at X- and/or Ka-bands, (8.4 GHz and/or 32 GHz, respectively). -- astro-ph.EP

Europa, Ganymede, Io, Jupiter, Missions & Hardware, Status Report

Planetary Radio Interferometry and Doppler Experiment as an Operational Component of the Jupiter Icy Moons Explorer Mission

by Keith CowingAugust 29, 2024August 28, 2024

We present an overview of the operations and engineering interface for Planetary Radio Interferometry and Doppler Experiment (PRIDE) radio astronomy observations as a scientific component of the ESA s Jupiter […]

Astrogeology, Biosignatures & Paleobiology, Europa, Ganymede, Habitable Zones, Icy Worlds, Jupiter, Mapping, Geodesy, Cartography, Bathymetry, Missions & Hardware, Status Report, Venus, Water/Hycean Worlds & Oceanography

Astrobiology Fleet Update: Video: Juice’s Lunar-Earth Flyby

by Keith CowingAugust 28, 2024August 27, 2024

On 19–20 August 2024, Juice successfully completed a world-first lunar-Earth flyby, with flight controllers guiding the spacecraft first past the Moon, then past Earth. The gravity of the two changed […]