The large icy satellites of Jupiter and Saturn are denser than pure water-ice and so must contain "rock" contaminants that can greatly affect each moon's geological (and hence possibly astrobiological) evolution. To understand these moons, we must determine the effect of the contaminants on the rheology of ice and so we are deforming ice-rock mixtures at UCL under triaxial conditions, to temperatures below 220 K (potentially ~100 K) and with confining pressures up to 300 MPa. The available data suggest that the difference in behaviour between ice-rock mixtures and pure ice may be strain-rate dependent. To fully understand the behaviour of the ice-rock system, we must measure the bulk deformation of samples whilst simultaneously determining the stress distribution between the rock and ice components; neutron diffraction using Engin-X is the best available method by which this may be done.