This proposal aims to exploit the superior flux on the upgraded HRPD coupled with the intrinsic high resolution to examine the differences between a sample of Sr2CoO2Cu1.85S2 which has been handled under rigorously anaerobic conditions and one which has been subjected to aerial oxidation. The compound shows exotic behaviour and provides valuable insight into the behaviour of strongly correlated electron systems. In particular the experiment will investigate the structural changes accompanying the negative thermal expansion of the pristine material at low temperatures and the increased flux at short d-spacings will allow close comparison of the bond lengths and atomic displacement parameters and their temperature dependence in the pristine and air-exposed materials. This experiment will be a good test of the upgraded HRPD and is intended as a commissioning experiment.