Related by context. Frequent words. (Click for all words.) 69 surfaces 56 subsurface 53 Surface 50 icy crust 49 coarse sand 48 glacial till 48 regolith 48 thin layer 47 coating 47 Martian surface 46 layer 46 nonporous 45 seafloor 45 lakebed 45 oceanic crust 45 overlying 45 silty 45 spalling 45 martian soil 45 surficial 45 martian surface 44 textured surfaces 44 conductivity 44 electrically conducting 44 surfacing 44 micrometre 44 surface roughness 44 clasts 44 bathymetry 44 lunar soil 44 compacted soil 44 soil 44 nanosized 43 outer shell 43 substrate 43 salt crystals 43 microstructures 43 Martian rocks 43 igneous rock 43 Martian landscape 42 Lake Vostok 42 beneath 42 calcrete 42 crust 42 seabed 42 iron oxides 42 sediments 42 edges 42 crustal 42 layers 42 earth crust 42 silicon substrate 42 dirt 42 granules 42 asphalt 42 spongy 42 subfloor 42 lithosphere 41 rubberized surface 41 Martian soil 41 macroscale 41 gravels 41 uneven surfaces 41 microscale 41 chemically inert 41 silicates 41 curved surfaces 41 silica 41 ejecta 41 sediment 41 oblique angle 41 solder joints 41 hardpan 40 scratches 40 polar vortex 40 twin rover Spirit 40 absorbs moisture 40 underneath 40 rubberized 40 ridges 40 roadbeds 40 Santa Anita synthetic 40 temperature gradient 40 magma chamber 40 blacktop 40 damp sponge 40 pebbly 40 Martian arctic 40 sandy 40 sidewalls 40 sand 40 protective coating 40 alluvium 40 roadbed 40 decomposed granite 40 crushed limestone 40 macadam 40 rubberised 40 cooling fins 40 quartz stockwork 40 interfacial