  We provide the first direct observations of interstellar H+ and He+ pickup
ions in the solar wind from 22 AU to 38 AU. We use the Vasyliunas and Siscoe
model functional form to quantify the pickup ion distributions, and while the
fit parameters generally lie outside their physically expected ranges, this
form allows fits that quantify variations in the pickup H+ properties with
distance. By ~20 AU, the pickup ions already provide the dominant internal
pressure in the solar wind. We determine the radial trends and extrapolate them
to the termination shock at ~90 AU, where the pickup H+ to core solar wind
density reaches ~0.14. The pickup H+ temperature and thermal pressure increase
from 22-38 AU, indicating additional heating of the pickup ions. This produces
very large extrapolated ratios of pickup H+ to solar wind temperature and
pressure and an extrapolated ratio of the pickup ion pressure to the solar wind
dynamic pressure at the termination shock of ~0.16. Such a large ratio has
profound implications for moderating the termination shock and the overall
outer heliospheric interaction. We also identify suprathermal tails in the H+
spectra and complex features in the He+ spectra, likely indicating variations
in the pickup ion history and processing. Finally, we discover enhancements in
both H+ and He+ populations just below their cutoff energies, which may be
associated with enhanced local pickup. This study serves to document the
release and as the citable reference of these pickup ion data for broad
community use and analysis.
