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Degradation of the organic molecules in the shallow subsurface of Mars due to irradiation by cosmic rays
Author(s) -
Pavlov A. A.,
Vasilyev G.,
Ostryakov V. M.,
Pavlov A. K.,
Mahaffy P.
Publication year - 2012
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2012gl052166
Subject(s) - mars exploration program , martian , cosmic ray , astrobiology , outcrop , geology , organic molecules , martian soil , solar system , life on mars , cosmic cancer database , organic matter , martian surface , earth science , geophysics , geochemistry , physics , astronomy , molecule , chemistry , organic chemistry , quantum mechanics
Detection of the organic matter on Mars is one of the main goals of the future Martian landing missions. Yet, the degradation of organic molecules by cosmic ray irradiation on Mars is often ignored. We calculate the radiation dose accumulation rates from solar and galactic cosmic rays at various depths in the shallow Martian subsurface. We demonstrate that a 1‐billion‐year outcrop on Mars accumulates the dosage of ∼500 MGy in the top 0–2 cm and ∼50 MGy at 5–10 cm depths. We show that the preservation of ancient complex organic molecules in the shallow (∼10 cm depth) subsurface of rocks could be highly problematic if the exposure age of a geologic outcrop would exceed 300 Myr. We demonstrate that more simple organic molecules with masses ∼100 amu should have a good chance to survive in the shallow subsurface of rocks. Implications to the sampling strategy for the oncoming Martian missions are discussed.