Non-thermal water loss of the early Mars: 3D multi-ion hybrid simulations |
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| Authors: | A Boesswetter H Lammer Y Kulikov U Motschmann S Simon |
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| Institution: | 1. Space Sciences Laboratory, University of California at Berkeley, 7 Gauss Way, Berkeley, CA 94720, USA;2. Space Science Institute, Macau University of Science and Technology, Avenida Wai Long, Taipa, Macau;3. Department of Physics and Astronomy, University of Kansas, Malott Hall, 1251 Wescoe Hall Dr., Lawrence, KS 66045, USA;4. LATMOS/IPSL-CNRS, Université Pierre et Marie Curie, Paris, France;5. Department of Engineering Physics, University of Virginia, Charlottesville, VA 22904, USA;6. Institutes of Astronomy and Space Science, National Central University, No. 300, Jhongda Rd, Jhongli City, Taoyuan County 32001, Taiwan, ROC;1. Research School of High–Energy Physics, National Research Tomsk Polytechnic University, Tomsk, 634050, Russia;2. Institut für Physikalische und Theoretische Chemie, Technische Universität Braunschweig, Braunschweig, D - 38106, Germany;1. Research School of High–Energy Physics, National Research Tomsk Polytechnic University, Tomsk 634050, Russia;2. Institut für Physikalische und Theoretische Chemie, Technische Universität Braunschweig, Braunschweig D-38106, Germany |
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| Abstract: | In this study we analyze the non-thermal loss rates of O+, O2+ and CO2+ ions over the last 4.5 billion years (Gyr) in the Martian history by using a 3D hybrid model. For this reason we derived the past solar wind conditions in detail. We take into account the intensified particle flux of the early Sun as well as an Martian atmosphere, which was exposed to a sun's extreme ultraviolet (EUV) radiation flux 4.5 Gyr ago that was 100 times stronger than today. Furthermore, we model the evolution of the interplanetary magnetic field by a Weber & Davis solar wind model. The ‘external’ influences of the Sun's radiation flux and solar wind flux lead to the formation of an ionospheric obstacle by photoionization, charge exchange and electron impact. For the early Martian conditions we could show that charge exchange was the dominant ionization mechanism. Several hybrid simulations for different stages in the evolution of the Martian atmosphere, at 1, 2, 5, 10, 30 and 100 EUV, were performed to analyze the non-thermal escape processes by ion pick-up, momentum transfer from the solar wind to the ionosphere and detached ionospheric plasma clouds. Our results show a non-linear evolution of the loss rates. Using mean solar wind parameters the simulations result in an oxygen loss equivalent to the depth of a global Martian ocean of about 2.6 m over the last 4.5 Gyr. The induced magnetic field strength could be increased up to about 2000 nT. A simulation run with high solar wind density results in an oxygen loss of a Martian ocean up to 205 m depth during 150 million years after the sun reached the zero age mean sequence (ZAMS). |
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