COUNTING CRACKING ACROSS THE SOLAR SYSTEM: HOW FRACTURE NETWORK TOPOLOGY INFORMS PROCESS

Crack networks are ubiquitous on planetary surfaces, across a vast range of scales and materials. From Earth's tectonic plates, to shattered icy crusts of Europa and Pluto, to putative mudcracks observed by the Mars rover Curiosity; all arise when thin sheets of sufficiently brittle material are stressed to the breaking point.

It was recently discovered that fracture networks may be well characterized as convex mosaics meaning that their topology is completely described by counting the numbers of vertices ($v$) and nodes ($n$) (see Domokos et al., 2020).

Experiments and simulations indicate that the topology of fracture networks is determined by the formative stress field, potentially allowing us to extract information about crack formation mechanisms from images of planetary surfaces.

Here we examine two-dimensional (2D) fracture mosaics on planetary surfaces across our solar system: Mars, Europa, Venus, and Pluto. Using the convex mosaics framework to count cracking patterns, we catalog these mosaics in terms of their average values $\bar{n}$ and $\bar{v}$. We are working to implement NEFI (Dirnberger et al. 2015) to extract the network skeletons and increase the rate at which we populate our data set.

Our measurements are able to discriminate between primary and secondary fracture patterns as well as patterns formed from cycles of repeated wetting and drying. Supplemented with laboratory experiments, we are able to track trajectories of $\bar{n}$ and $\bar{v}$ over multiple fracturing events. Current observation indicates that the cracked planetary shells we study lie somewhere along these trajectories, having formed from a complex fracture history.