New Paths for Survivability of Organic Material in the Martian Subsurface

摘要

Recent space missions have identified organics, chlorinated and non-chlorinated, on Mars. Understanding the origin, current state and reactivity of this carbonaceous material is critical to efforts to detect organic signatures of possible past life on Mars. Environmental effects such as ultraviolet radiation, pressure, diagenesis, aqueous activity, and presence of perchlorates have been assessed previously using analog experiments. To this list, Fox, et al. adds and quantifies the effect of galactic cosmic rays and solar winds on organic material on the surface and in the near subsurface of Mars. Their work, using laboratory analog materials and radiation, shows that the same organic acids, formic and oxalic acid, are produced after exposure equivalent to that over Martian history at depths of less than 5 cm, independent of mineral matrix or starting organic materials. These experiments suggest that planned subsurface exploration using the drill on the Rosalind Franklin Rover (ExoMars) will sample organic material which has not been altered by cosmic rays, although it may have been exposed to other environmental factors such as water or salts.