Coefficient of restitution as a function of temperature. There is no correlation between the two parameters. The chemical compositions are indicated by different colours: black for pure water ice, red for 5% methanol in water, and blue for 5% formic acid in water. The symbols indicate the orientation of the target; a plus symbol for the target surface at 90° to the direction of travel, and a square for the target surface at 60° to the direction of travel.