Diurnal sublimation rates for a sublimation front at the surface and at a depth of 3 mm calculated for a heliocentric distance of 3.5 AU. The solar irradiation pattern for a flat surface is shown in comparison (boldface, dashed line); values are restricted to the 6.2 h in direct illumination conditions. Fractures A2 (dotted line) and A6 (dashed line) have sublimating floors. All calculations were performed for a solar plane angle of 30° and sublimation originating only from the fracture bottom.