  The experimental characterization of scattering resonances in low energy
collisions has proven to be a stringent test for quantum chemistry
calculations. Previous measurements on the NO-H$_2$ system at energies down to
$10$ cm$^{-1}$ challenged the most sophisticated calculations of potential
energy surfaces available. In this report, we continue these investigations by
measuring the scattering behavior of the NO-H$_2$ system in the previously
unexplored $0.4 - 10$ cm$^{-1}$ region for the parity changing de-excitation
channel of NO. We study state-specific inelastic collisions with both
\textit{para}- and \textit{ortho}-H$_2$ in a crossed molecular beam experiment
involving Stark deceleration and velocity map imaging. We are able to resolve
resonance features in the measured integral and differential cross sections.
Results are compared to predictions from two previously available potential
energy surfaces and we are able to clearly discriminate between the two
potentials. We furthermore identify the partial wave contributions to these
resonances, and investigate the nature of the differences between collisions
with \textit{para}- and \textit{ortho}-H$_2$. Additionally, we tune the energy
spreads in the experiment to our advantage to probe scattering behavior at
energies beyond our mean experimental limit.
