  We have obtained Spitzer IRS 5.5 - 35 micron spectroscopy of the debris disk
around beta Pictoris. In addition to the 10 micron silicate emission feature
originally observed from the ground, we also detect the crystalline silicate
emission bands at 28 micron and 33.5 micron. This is the first time that the
silicate bands at wavelengths longer than 10 micron have ever been seen in the
beta Pictoris disk. The observed dust emission is well reproduced by a dust
model consisting of fluffy cometary and crystalline olivine aggregates. We
searched for line emission from molecular hydrogen and atomic [S I], Fe II, and
Si II gas but detected none. We place a 3 sigma upper limit of <17 Earth masses
on the H2 S(1) gas mass, assuming an excitation temperature of Tex = 100 K.
This suggests that there is less gas in this system than is required to form
the envelope of Jupiter. We hypothesize that some of the atomic Na I gas
observed in Keplerian rotation around beta Pictoris may be produced by
photon-stimulated desorption from circumstellar dust grains.
