  Recently, deuterium has been the focus of a high level of experimental and
theoretical activity that was sparked by a disagreement on the experimental
value of the maximum compression along the Hugoniot. The behavior of deuterium
at Mbar pressures is not well understood.
  It is of great interest to understand how the current uncertainty on the
hydrogen/deuterium EOS affects the inferred structures of Jupiter and Saturn.
In particular, the mass of a core of heavy elements (other than H and He) and
the total mass of those heavy elements in these two planets are quite sensitive
to the EOS of hydrogen and constitute important clues to their formation
process. We present a study of the range of structures allowed for Jupiter and
Saturn by the current uncertainty in the hydrogen EOS and astrophysical
observations of the two planets. An improved experimental understanding of
hydrogen at Mbar pressures and better determinations of the gravitational
moments of both planets are necessary to put tight bounds on their internal
structure.
