Conamara Chaos Region, Europa: Reconstruction of mobile polygonal ice blocks

New Galileo images of Europa reveal regions of chaotic terrain in otherwise highly-lineated background plains. Examination of Conamara Chaos shows tha t 59% of the region is composed of fine-textured matrix material lying at l ow elevations and formed by destruction of lineated plains, while the remai nder consists of 139 fragmented polygons of linear-textured background plai ns. Using through-trending linear features, we reconstruct the original pos itions of chaos polygons and find that significant lateral translation and rotation have occurred: 78% of the polygons have undergone horizontal trans lations with most moving between I and 5 km, and 81% have rotated (average rotation of similar to 11 degrees). Movement of polygons appears to be inwa rd from the chaos margins and clockwise in the center, while polygon rotati on is evenly clockwise and counterclockwise. Chaos formation in this region thus involves destruction of over half of the pre-existing terrain, and mo bilization, translation, and rotation of the remaining polygons, implying e levated near-surface temperatures and a highly mobile substrate over latera l scales of similar to 100 km.