Galilean satellites Archives - Astrobiology

(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 […]

Block diagram of the proposed multi-physics simulation model LunaIcy. -- astro-ph.EP

Astrogeology, Biogeochemical Cycles & Geobiology, Callisto, Cryobiology, Europa, Ganymede, Habitable Zones, Icy Worlds, Imaging & Spectroscopy, Mapping, Geodesy, Cartography, Bathymetry, Status Report, Water/Hycean Worlds & Oceanography

LunaIcy: Exploring Europa’s Icy Surface Microstructure through Multiphysics Simulations

by Keith CowingOctober 22, 2024October 22, 2024

A multiphysics simulation model incorporating a sintering model coupled with the MultIHeaTS thermal solver was developed to study the evolution of icy moons’ microstructure.

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 […]

Io, Europa, Ganymede, and Callisto. Credit: NASA/JPL/DLR

Biogeochemical Cycles & Geobiology, Callisto, Europa, Ganymede, Icy Worlds, Imaging & Spectroscopy, Io, Jupiter, Radiation, Status Report

Energy And Temperature Dependencies For Electron-induced Sputtering From H2O-ice: Implications For The Icy Galilean Moons

by Keith CowingMay 9, 2024May 9, 2024

To better assess the role that electrons play in exosphere production on icy-rich bodies, we measured the total and O2 sputtering yields from H2O-ice for electrons with energies between 0.75 […]

Water ice on the surface of Europa is dissociated by radiolysis to form O2 and H2. These gases can migrate both inwards towards the subsurface ocean or escape the surface by thermal desorption or direct sputtering to form its atmosphere. The lighter H2 occupies a more extended region than heavier O2, which remains closer to the surface. A portion of the neutrals in the atmosphere are ionized and picked up by the magnetospheric plasma. Juno observes these PUIs, with the relative abundances driven by the various processes described here. The radiolysis dissociation inset was adapted from ref. 2. Particles shown are O2 (blue), H2 (pink) and H2+ (grey). -- NASA/Nature Astronomy

Astrochemistry, Astrogeology, Atmospheres, Climate, Weather, Biochemistry & Organic Chemistry, Biosignatures & Paleobiology, Europa, Habitable Zones, Icy Worlds, Imaging & Spectroscopy, Jupiter, Press Release

Juno Measures The Rate Of Oxygen Production At Europa

by Keith CowingMarch 4, 2024March 4, 2024

Scientists with NASA’s Juno mission to Jupiter have calculated the rate of oxygen being produced at the Jovian moon Europa to be substantially less than most previous studies.

Detections

Callisto, Europa, Ganymede, Icy Worlds, Imaging & Spectroscopy, Space Weather & Heliophysics, Status Report

The Optical Aurorae of Europa, Ganymede and Callisto

by Keith CowingFebruary 17, 2023February 17, 2023

The tenuous atmospheres of the Galilean satellites are sourced from their surfaces and produced by a combination of plasma-surface interactions and thermal processes. Though thin, these atmospheres can be studied […]