Solar cells based on a layer of halide perovskite have recently seen rapid increases in efficiency, with certified values in excess of 20%. The prototypical material of this class is the methyl-ammonium-containing halide perovskite CH3NH3PbI3. Very recently, the phase transitions and dynamic disorder of this structure, which has been extensively studied since the eighties, have come under renewed scrutiny, since they appear to be related to key PV performance parameters. Here, we propose to study for the first time the dynamics of the CH3NH3 organic molecule via quasi-elastic neutron scattering, on OSIRIS. This will allow the detailed study of the CH3NH3 reorientation and its effect on the phase transitions and symmetry of the low temperature phases. Additionally we propose the measurement of a fully deuterated sample to investigate dynamical correlations between CH3NH3 molecules.