Scanning electron microscope images of typical particles of prototype simulants of 2016 HO3. (a) Overview of H group prototype simulant QLS-1 particles in various sizes and shapes. The inset white square indicates where the image (b) is taken. (b) Zoom in of image (a) showing mixture of large and fine grains. (c) LL group prototype simulant QLS-3. (d) Fines coating the surface of a larger grain in the L group prototype simulant.