Planetary atmospheres

Abstract

Loss of gases from the terrestrial planets is discussed in the context of meteorites and their parent bodies. The present inventories of C, N and noble gases are discussed and tabulated for these bodies and for icy ones as well. Gases trapped in SNC meteorites are adopted as representing Mars. The principal loss processes (large impact, thermal escape and nonthermal escape) are outlined, with emphasis on recent developments such as diffusion limits and fractionation in hydrodynamic escape. A series of case studies consider the effects of hydrodynamic escape, and D and noble gases on Venus. -Authors