  We present a practical roadmap to achieve optical cycling and laser cooling
of asymmetric top molecules (ATMs). Our theoretical analysis describes how
reduced molecular symmetry, as compared to diatomic and symmetric non-linear
molecules, plays a role in photon scattering. We present methods to circumvent
limitations on rapid photon cycling in these systems. We calculate vibrational
branching ratios for a diverse set of asymmetric top molecules and find that
many species within a broad class of molecules can be effectively cooled with a
manageable number of lasers. We also describe methods to achieve rotationally
closed optical cycles in ATMs. Despite significant structural complexity, laser
cooling can be made effective using extensions of the current techniques used
for linear molecules. Potential scientific impacts of laser-cooled ATMs span
frontiers in controlled chemistry, quantum simulation, and searches for physics
beyond the Standard Model.
