  Synchronous binary asteroids may exist in a long-term stable equilibrium,
where the opposing torques from mutual body tides and the binary YORP (BYORP)
effect cancel. Interior of this equilibrium, mutual body tides are stronger
than the BYORP effect and the mutual orbit semi-major axis expands to the
equilibrium; outside of the equilibrium, the BYORP effect dominates the
evolution and the system semi-major axis will contract to the equilibrium. If
the observed population of small (0.1 - 10 km diameter) synchronous binaries
are in static configurations that are no longer evolving, then this would be
confirmed by a null result in the observational tests for the BYORP effect. The
confirmed existence of this equilibrium combined with a shape model of the
secondary of the system enables the direct study of asteroid geophysics through
the tidal theory. The observed synchronous asteroid population cannot exist in
this equilibrium if described by the canonical "monolithic" geophysical model.
The "rubble pile" geophysical model proposed by \citet{Goldreich2009} is
sufficient, however it predicts a tidal Love number directly proportional to
the radius of the asteroid, while the best fit to the data predicts a tidal
Love number inversely proportional to the radius. This deviation from the
canonical and \citet{Goldreich2009} models motivates future study of asteroid
geophysics. Ongoing BYORP detection campaigns will determine whether these
systems are in an equilibrium, and future determination of secondary shapes
will allow direct determination of asteroid geophysical parameters.
