Stability of Organics in the Presence of Perchlorates on the Martian Surface

The primary objective of this project is to unravel the chemical and physical processes associated with the destruction of organics under simulated Mars surface conditions in the presence of perchlorates. In order to fully explore the destruction of organics, we have first systematically studied the energetic decomposition of pure perchlorates such as magnesium perchlorate hexahydrate Mg(ClO₄)₂∙6H₂O at Mars relevant temperatures in order to trace the chemistry and source of reactive species. Magnesium perchlorate was chosen for this study as it has been suggested to be the most likely form of perchlorate in Martian regolith. Following the destruction of perchlorates, we explored the catalytic formation of perchlorates on the Martian surface via Galactic Cosmic Rays via modeling. Thereafter, we systematically explored the radiolytic destruction of key representative of amino acids and RNA nitrogen bases [glycine, adenine] of the pure compounds and in the presence of magnesium perchlorate with the former serving as the baseline for comparison with homogenous mixtures of the organics with magnesium perchlorate.

nasamars_1 — The Phoenix lander (left) discovered perchlorate [ClO₄]^– salts within the Martian regolith (right) utilizing the Wet Chemistry Lab (WCL). The insert shows the structure of the perchlorate ion with chlorine and oxygen atoms shown in green and red, respectively.

nasamars_2 — The Phoenix lander (left) discovered perchlorate [ClO₄]^– salts within the Martian regolith (right) utilizing the Wet Chemistry Lab (WCL). The insert shows the structure of the perchlorate ion with chlorine and oxygen atoms shown in green and red, respectively.

nasamars_3 — Chlorine map with locations of landing sites; MSL landed at the Gale crater (‘G’) shown far right, Phoenix landed near the pole at 68° N and 54° W. Although this map does not elucidate perchlorates explicitly, as the detection method used could not distinguish the oxidative state of chlorine, the Phoenix lander found that *most of the chlorine was in the form of perchlorates*. Therefore, a reasonable hypothesis in the Mars community is that this map indirectly reflects at least the trend of perchlorate concentration.

Recent Selected Publications

1. Y.S. Kim, K.P. Wo, S. Maity, S.K. Atreya, and R.I. Kaiser, Radiation-Induced Formation of Chlorine Oxides and Their Potential Role in the Origin of Martian Perchlorates, JACS, 135, 4910-4913 (2013). (PDF)

2. A.M. Turner, M.J. Abplanalp, R.I. Kaiser, Mechanistic Studies on the Radiolytic Decomposition of Perchlorates on the Martian Surface, Ap. J. 820, 127 (2016). (PDF)

3. S. Góbi, M.J. Abplanalp, R.I. Kaiser, Effect of Perchlorates on Electron Radiolysis of Glycine with Application to Mars, Ap. J. 822, 8 (2016). (PDF)

4. E.H. Wilson, S.K. Atreya, R.I. Kaiser, Perchlorate Formation on Mars through Surface Radiolysis Initiated Atmospheric Chemistry : A Potential Mechanism, Journal of Geophysical Research – Planets, 121, 1472-1487 (2016). (PDF)

5. S. Góbi, A. Bergantini, R. I. Kaiser, In Situ Detection of Chlorine Dioxide (ClO₂) in the Radiolysis of Perchlorates and Implications for the Stability of Organics on Mars, Ap. J., 832, 164 (2016). (PDF)

6. S. Góbi, M. Förstel, P. Maksyutenko, R.I. Kaiser, A Reflectron Time-of-Flight Mass Spectrometric Study on the Degradation Pathways of Glycine on Mars in the Presence of Perchlorates and Ionizing Radiation, Ap. J., 835, 241 (2017). (PDF)

7. S. Góbi, A. Bergantini, R.I. Kaiser, Degradation of Adenine on the Martian Surface in the Presence of Perchlorates and Ionizing Radiation: A Reflectron Time-of-flight Mass Spectrometric Study, J. ApJ, 838, 84 (2017). (PDF)

8. P.B. Crandall, S. Góbi, J. Gillis-Davis, R.I. Kaiser, Can perchlorates be transformed to hydrogen peroxide (H₂O₂) products by cosmic rays on the Martian surface?, J. Geophys. Res. Planets, 122, 1880-1892 (2017). (PDF)