The Geodesy and Geophysics of Jupiter and the Galilean Moons (3GM) experiment aboard the JUpiter ICy moons Explorer (JUICE) will estimate the gravity fields of Europa, Callisto and Ganymede. For Ganymede, a 9-months orbital phase is planned, divided in a 5-month elliptical phase and a 4-month circular orbit. This latter will allow to obtain the first orbital gravity data for Ganymede, enabling the estimation of Ganymede’s gravity field up to degree 30-40 of the spherical harmonics expansion. Moreover, the collected data will allow the identification of regional (hundreds of km) surface structures. Ganymede’s icy surface shell is characterized by the presence of dark and bright terrains: evidence of older, dirty ice, and younger, clean ice, respectively. In this work we investigate the possibility to detect gravity anomalies related to the surface distribution of bright and dark terrains using the 3GM data. To this aim, we simulate the expected gravity field as it would be reconstructed by JUICE by assuming: i) a range of reasonable density contrasts and thicknesses for the dark and bright terrains; ii) a set of models for the surface topographies based on Galileo probe images (e.g. Golombek, 1982; Parmentier et al., 1982; Squyres, 1981; Giese et al., 1998; Schenk et al., 2001); iii) a multi-layered internal structure model (Hemingway & Matsuyama, 2017) assuming isostatic compensation; iv) a conductive heat transfer model for the icy shell, the ocean and the sub-oceanic high-pressure icy layers (Mitri et al., 2010). Our results show that 3GM data may allow to discriminate and separate the gravitational contributions from the deep interior and the surface distribution of dark and bright terrains. Moreover, we show that the presence of a deep ocean below the ice shell could be inferred from a peculiar profile of the power spectrum of the measured gravity signal.
Observability of Ganymede’s gravity anomalies related to surface features by the 3GM experiment onboard European Space Agency (ESA) JUpiter ICy moons Explorer (JUICE) mission / DE MARCHI, Fabrizio; Di Achille, Gaetano; Mitri, Giuseppe; Cappuccio, Paolo; DI STEFANO, Ivan; Iess, Luciano. - (2020), pp. 24-24. (Intervento presentato al convegno XVI congresso nazionale di scienze planetarie tenutosi a Padova).
Observability of Ganymede’s gravity anomalies related to surface features by the 3GM experiment onboard European Space Agency (ESA) JUpiter ICy moons Explorer (JUICE) mission
Fabrizio De Marchi
Primo
;Paolo Cappuccio;Ivan di Stefano;Luciano Iess
2020
Abstract
The Geodesy and Geophysics of Jupiter and the Galilean Moons (3GM) experiment aboard the JUpiter ICy moons Explorer (JUICE) will estimate the gravity fields of Europa, Callisto and Ganymede. For Ganymede, a 9-months orbital phase is planned, divided in a 5-month elliptical phase and a 4-month circular orbit. This latter will allow to obtain the first orbital gravity data for Ganymede, enabling the estimation of Ganymede’s gravity field up to degree 30-40 of the spherical harmonics expansion. Moreover, the collected data will allow the identification of regional (hundreds of km) surface structures. Ganymede’s icy surface shell is characterized by the presence of dark and bright terrains: evidence of older, dirty ice, and younger, clean ice, respectively. In this work we investigate the possibility to detect gravity anomalies related to the surface distribution of bright and dark terrains using the 3GM data. To this aim, we simulate the expected gravity field as it would be reconstructed by JUICE by assuming: i) a range of reasonable density contrasts and thicknesses for the dark and bright terrains; ii) a set of models for the surface topographies based on Galileo probe images (e.g. Golombek, 1982; Parmentier et al., 1982; Squyres, 1981; Giese et al., 1998; Schenk et al., 2001); iii) a multi-layered internal structure model (Hemingway & Matsuyama, 2017) assuming isostatic compensation; iv) a conductive heat transfer model for the icy shell, the ocean and the sub-oceanic high-pressure icy layers (Mitri et al., 2010). Our results show that 3GM data may allow to discriminate and separate the gravitational contributions from the deep interior and the surface distribution of dark and bright terrains. Moreover, we show that the presence of a deep ocean below the ice shell could be inferred from a peculiar profile of the power spectrum of the measured gravity signal.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
