Discovery of Mass Anomalies on Ganymede
John D. Anderson,1*
Gerald Schubert,2,3
Robert A. Jacobson,1
Eunice L. Lau,1
William B. Moore,2
Jennifer L. Palguta2
We present the discovery of mass anomalies on Ganymede, Jupiter's
third and largest Galilean satellite. This discovery is surprising
for such a large icy satellite. We used the radio Doppler data
generated with the Galileo spacecraft during its second encounter
with Ganymede on 6 September 1996 to model the mass anomalies.
Two surface mass anomalies, one a positive mass at high latitude
and the other a negative mass at low latitude, can explain the
data. There are no obvious geological features that can be identified
with the anomalies.
2 Department of Earth and Space Sciences, University of California, Los Angeles, CA 90095–1567, USA.
3 Institute of Geophysics and Planetary Physics, Los Angeles, CA 90095–1567, USA.
* To whom correspondence should be addressed; E-mail: john.d.anderson{at}jpl.nasa.gov
