  We study the inhomogeneous clustered regime of a freely cooling granular gas
of rough particles in two dimensions using large-scale event driven simulations
and scaling arguments. During collisions, rough particles dissipate energy in
both the normal and tangential directions of collision. In the inhomogeneous
regime, translational kinetic energy and the rotational energy decay with time
$t$ as power-laws $t^{-\theta_T}$ and $t^{-\theta_R}$. We numerically determine
$\theta_T \approx 1$ and $\theta_R \approx 1.6$, independent of the
coefficients of restitution. The inhomogeneous regime of the granular gas has
been argued to be describable by the ballistic aggregation problem, where
particles coalesce on contact. Using scaling arguments, we predict $\theta_T=1$
and $\theta_R=1$ for ballistic aggregation, $\theta_R$ being different from
that obtained for the rough granular gas. Simulations of ballistic aggregation
with rotational degrees of freedom are consistent with these exponents.
