[en] The surface of Ganymede exhibits diversity in composition, interpreted as indicative of geological age differences between dark and bright terrains. Observations from Galileo and Earth-based telescopes have revealed the presence of both water ice and non-ice material, indicative of either endogenic or exogenic processes, or some combination. However, these observations attained a spatial resolution that was too coarse to reveal the surface composition at a local scale. Here we present the high-spatial-resolution infrared spectra of Ganymede observed with the Jovian InfraRed Auroral Mapper onboard the National Aeronautics and Space Administration’s Juno spacecraft during a close flyby that occurred on 7 June 2021. We found that at a pixel resolution <1 km, the surface of Ganymede exhibits signatures diagnostic of hydrated sodium chloride, ammonium chloride and sodium/ammonium carbonate, as well as organic compounds, possibly including aliphatic aldehydes. Carbon dioxide shows up mostly at trailing longitudes. The composition and spatial distribution of these salts and organics suggest that their origin is endogenic, resulting from the extrusion of subsurface brines, whose chemistry reflects the water–rock interaction inside Ganymede.
Research Center/Unit :
STAR - Space sciences, Technologies and Astrophysics Research - ULiège
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Tosi, Federico ; Istituto Nazionale di Astrofisica–Istituto di Astrofisica e Planetologia Spaziali, Rome, Italy
Mura, Alessandro; Istituto Nazionale di Astrofisica–Istituto di Astrofisica e Planetologia Spaziali, Rome, Italy
Cofano, Alessandra ; Istituto Nazionale di Astrofisica–Istituto di Astrofisica e Planetologia Spaziali, Rome, Italy
Zambon, Francesca; Istituto Nazionale di Astrofisica–Istituto di Astrofisica e Planetologia Spaziali, Rome, Italy
Glein, Christopher R.; Southwest Research Institute, San Antonio, United States
Ciarniello, Mauro ; Istituto Nazionale di Astrofisica–Istituto di Astrofisica e Planetologia Spaziali, Rome, Italy
Lunine, Jonathan I. ; Cornell University, Ithaca, United States
Piccioni, Giuseppe; Istituto Nazionale di Astrofisica–Istituto di Astrofisica e Planetologia Spaziali, Rome, Italy
Sordini, Roberto ; Istituto Nazionale di Astrofisica–Istituto di Astrofisica e Planetologia Spaziali, Rome, Italy
Adriani, Alberto; Istituto Nazionale di Astrofisica–Istituto di Astrofisica e Planetologia Spaziali, Rome, Italy
Bolton, Scott J. ; Southwest Research Institute, San Antonio, United States
Hansen, Candice J.; Planetary Science Institute, Tucson, United States
Nordheim, Tom A.; Jet Propulsion Laboratory, California Institute of Technology, Pasadena, United States
Moirano, Alessandro ; Université de Liège - ULiège > Département d'astrophysique, géophysique et océanographie (AGO) > Labo de physique atmosphérique et planétaire (LPAP) ; Istituto Nazionale di Astrofisica–Istituto di Astrofisica e Planetologia Spaziali, Rome, Italy ; Università degli Studi di Roma ‘La Sapienza’, Rome, Italy
Agostini, Livio ; Istituto Nazionale di Astrofisica–Istituto di Astrofisica e Planetologia Spaziali, Rome, Italy
Altieri, Francesca; Istituto Nazionale di Astrofisica–Istituto di Astrofisica e Planetologia Spaziali, Rome, Italy
Brooks, Shawn M.; Jet Propulsion Laboratory, California Institute of Technology, Pasadena, United States
Cicchetti, Andrea ; Istituto Nazionale di Astrofisica–Istituto di Astrofisica e Planetologia Spaziali, Rome, Italy
Dinelli, Bianca Maria; Consiglio Nazionale delle Ricerche–Istituto di Scienze dell’Atmosfera e del Clima, Bologna, Italy
Grassi, Davide; Istituto Nazionale di Astrofisica–Istituto di Astrofisica e Planetologia Spaziali, Rome, Italy
Migliorini, Alessandra ; Istituto Nazionale di Astrofisica–Istituto di Astrofisica e Planetologia Spaziali, Rome, Italy
Moriconi, Maria Luisa; Istituto Nazionale di Astrofisica–Istituto di Astrofisica e Planetologia Spaziali, Rome, Italy
Noschese, Raffaella ; Istituto Nazionale di Astrofisica–Istituto di Astrofisica e Planetologia Spaziali, Rome, Italy
Scarica, Pietro; Istituto Nazionale di Astrofisica–Istituto di Astrofisica e Planetologia Spaziali, Rome, Italy
Sindoni, Giuseppe ; Agenzia Spaziale Italiana, Rome, Italy
Stefani, Stefania; Istituto Nazionale di Astrofisica–Istituto di Astrofisica e Planetologia Spaziali, Rome, Italy
Turrini, Diego ; Istituto Nazionale di Astrofisica–Osservatorio Astrofisico di Torino, Pino Torinese, Italy
ASI - Agenzia Spaziale Italiana NASA - National Aeronautics and Space Administration
Funding text :
The JIRAM instrument is funded by the Italian Space Agency (Agenzia Spaziale Italiana (ASI)). It was built by Selex ES under the leadership of the Italian National Institute for Astrophysics (Istituto Nazionale di Astrofisica (INAF))–Institute for Space Astrophysics and Planetology (Istituto di Astrofisica e Planetologia Spaziali (IAPS)), Rome, Italy. JIRAM is operated by INAF–IAPS, Rome, Italy. F.T., A. Mura, A. Cofano, F.Z., M.C., G.P., C.P., R.S., A.A., A. Migliorini, L.A., F.A., A. Cicchetti, B.M.D., D.G., A. Moirano, M.L.M., R.N., P.S., G.S., S.S. and D.T. acknowledge the support from the ASI–INAF grant no. 2016-23-H.0 plus addendum no. 2016-23-H.2-2021. C.R.G. was supported in part by the NASA grants NNN13D485T and 80NSSC19K0611. Support for S.J.B. and the Juno project is provided under the NASA grant NNM06AA75C to the Southwest Research Institute. J.I.L. acknowledges support from the Juno mission through subcontract D99069MO from the Southwest Research Institute. C.J.H. acknowledges support from the Juno project through a subcontract from the Southwest Research Institute. T.A.N. was supported by the NASA grant 80NM0018F0612. Support from the Juno Science and Operations Teams is gratefully acknowledged.The JIRAM instrument is funded by the Italian Space Agency (Agenzia Spaziale Italiana (ASI)). It was built by Selex ES under the leadership of the Italian National Institute for Astrophysics (Istituto Nazionale di Astrofisica (INAF))–Institute for Space Astrophysics and Planetology (Istituto di Astrofisica e Planetologia Spaziali (IAPS)), Rome, Italy. JIRAM is operated by INAF–IAPS, Rome, Italy. F.T., A. Mura, A. Cofano, F.Z., M.C., G.P., C.P., R.S., A.A., A. Migliorini, L.A., F.A., A. Cicchetti, B.M.D., D.G., A. Moirano, M.L.M., R.N., P.S., G.S., S.S. and D.T. acknowledge the support from the ASI–INAF grant no. 2016-23-H.0 plus addendum no. 2016-23-H.2-2021. C.R.G. was supported in part by the NASA grants NNN13D485T and 80NSSC19K0611. Support for S.J.B. and the Juno project is provided under the NASA grant NNM06AA75C to the Southwest Research Institute. J.I.L. acknowledges support from the Juno mission through subcontract D99069MO from the Southwest Research Institute. C.J.H. acknowledges support from the Juno project through a subcontract from the Southwest Research Institute. T.A.N. was supported by the NASA grant 80NM0018F0612. Support from the Juno Science and Operations Teams is gratefully acknowledged.
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