a1 Department of Astronomy, Cornell University, 402 Space
Sciences Building, Ithaca, NY 14853 USA email:
firstname.lastname@example.org The giant planets of our solar
system contain a record of elemental and isotopic ratios of keen
interest for what they tell us about the origin of the planets
and in particular the volatile compositions of the solid phases.
In situ measurements of the Jovian atmosphere performed by the
Galileo Probe during its descent in 1995 demonstrate the unique
value of such a record, but limited currently by the unknown
abundance of oxygen in the interior of Jupiter–a gap planned to
be filled by the Juno mission set to arrive at Jupiter in July
of 2016. Our lack of knowledge of the oxygen abundance allows
for a number of models for the Jovian interior with a range of
C/O ratios. The implications for the origin of terrestrial water
are briefly discussed. The complementary data sets for Saturn
may be obtained by a series of very close, nearly polar orbits,
at the end of the Cassini-Huygens