Origin and stability of lunar polar volatiles

Abstract Temperature regime at the LCROSS impact site is studied. All detected species in the Cabeus crater as well as CH 4 and CO clathrate hydrates except H 2 , CO, and CH 4 are stable against evaporation at the LCROSS impact site. CO and CH 4 can be chemisorbed at the surface of the regolith particles and exist in the form of clathrate hydrates in the lunar cold traps. Flux rates of delivery of volatile species by asteroids, micrometeoroids, O-rich, C-rich, and low-speed comets into the permanently shadowed regions are estimated. Significant amounts of H 2 O, CO, H 2 , H 2 S, SO 2 , and CO 2 can be impact-produced during collisions between asteroids and O-rich comets with the Moon while CH 3 OH, NH 3 and complex organic species survive during low-speed comet impacts as products of disequilibrium processes. C-rich comets are main sources of CH 4 , and C 2 H 4 .