Mass Anomalies on GanymedeRadio Doppler data from two Ganymede encounters (G1 and G2) on the first two orbits in the Galileo mission have been analyzed previously for gravity information . For a satellite in hydrostatic equilibrium, its gravitational field can be modeled adequately by a truncated spherical harmonic series of degree two. However, a fourth degree field is required in order to fit the second Galileo flyby (G2). This need for a higher degree field strongly suggests that Ganymede s gravitational field is perturbed by a gravity anomaly near the G2 closest approach point (79.29 latitude, 123.68 west longitude). In fact, a plot of the Doppler residuals , after removal of the best-fit model for the zero degree term (GM) and the second degree moments (J2 and C22), suggests that if an anomaly exists, it is located downtrack of the closest approach point, closer to the equator.
Document ID
20040055887
Acquisition Source
Johnson Space Center
Document Type
Conference Paper
Authors
Schubert, G. (California Univ. Los Angeles, CA, United States)
Anderson, J. D. (Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Jacobson, R. A. (Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Lau, E. L. (Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Moore, W. B. (California Univ. Los Angeles, CA, United States)
Palguta, J. (California Univ. Los Angeles, CA, United States)
Date Acquired
August 21, 2013
Publication Date
January 1, 2004
Publication Information
Publication: Lunar and Planetary Science XXXV: Icy Worlds: Moving and Grooving