  An estimate is made of the thickness of the radar-bright deposits in craters
near to the north pole of Mercury. To construct an objective set of craters for
this measurement, an automated crater finding algorithm is developed and
applied to a digital elevation model based on data from the Mercury Laser
Altimeter on board the MESSENGER spacecraft. This produces a catalogue of 663
craters with diameters exceeding 4 km, northwards of latitude +55 degrees. A
subset of 12 larger, well-sampled and fresh polar craters are selected to
search for correlations between topography and radar same-sense backscatter
cross-section. It is found that the typical excess height associated with the
radar-bright regions within these fresh polar craters is (50+/-35)m. This puts
an approximate upper limit on the total polar water ice deposits on Mercury of
3e15 kg.
