  We investigated 634 crater clusters on Mars detected between 2007 and 2021,
which represent more than half of all impacts discovered in this period. Crater
clusters form when meteoroids in the 10 kg to 10 ton mass range break-up in
Mars' atmosphere to produce a few to a few hundred fragments that hit the
ground. The properties of the clusters can inform our understanding of
meteoroid properties and the processes that govern their fragmentation. We
mapped individual craters $>$1 m within each cluster and defined a range of
cluster properties based on the spatial and size distributions of the craters.
The large data set, with over eight times more cluster observations than
previous work, provides a more robust statistical investigation of crater
cluster parameters and their correlations. Trends in size, dispersion and large
crater fraction with elevation support weak atmospheric filtering of material.
The diversity in the number of individual craters within a cluster, and their
size-frequency distributions, may reflect either a diversity in fragmentation
style, fragility or internal particle sizes.
