Abstract

We present the model calculation results of the atomic oxygen loss rate from the Martian atmosphere induced by precipitation of high-energy protons and hydrogen atoms (H/H⁺) from the solar wind plasma. Penetration of energetic protons and hydrogen atoms from the solar wind plasma to the upper atmosphere of Mars at altitudes of 100−250 km is accompanied by the momentum and energy transfer in collisions with the main component, atomic oxygen. This process is considered as atmospheric gas sputtering during proton auroral events, which is accompanied by formation of the suprathermal hydrogen and oxygen atom fluxes escaping from the atmosphere. When calculating the formation rate of suprathermal atoms, the modified Monto Carlo kinetic model was used. This model was earlier developed to analyze the data of the Analyzer of Space Plasma and Energetic Atoms (ASPERA-3) and the Solar Wind Ion Analyzer (SWIA) onboard the Mars Express (MEX) and the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft, respectively. We study the processes of kinetics and transport of hot oxygen atoms in the transition zone (from the thermosphere to the exosphere) of Mars’ upper atmosphere. The kinetic energy distribution functions for suprathermal oxygen atoms were calculated. It has been shown that, during proton auroral events on Mars, the exosphere is populated with a significant number of suprathermal oxygen atoms, the kinetic energy of which reaches the escape energy, 2 eV. In addition to photochemical sources, a hot fraction is formed in the oxygen corona; and a nonthermal flux of atomic oxygen escaping from the Martian atmosphere is produced during proton aurora events. Proton aurorae are sporadic auroral events. Consequently, according to the estimates obtained from the recent MAVEN observations the magnitude of the precipitation-induced escaping flux of hot oxygen atoms may become prevailing over the photochemical sources under conditions of the extreme solar events such as solar flares and coronal mass ejections.

中文翻译：

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质子极光事件期间火星大气中的氧气原子逸出

摘要

我们提出了由高能质子和氢原子（H / H ⁺）来自太阳风等离子体。高能质子和氢原子从太阳风等离子体渗透到100-250 km高度的火星上层大气，伴随着与主要成分原子氧碰撞的动量和能量转移。该过程被认为是质子极光事件期间的大气溅射，伴随有从大气逸出的超热氢和氧原子通量的形成。在计算超热原子的形成速率时，使用了改进的Monto Carlo动力学模型。该模型是较早开发的，用于分析火星快车（MEX）和火星大气与挥发性演化（MAVEN）航天器上的空间等离子体和高能原子分析仪（ASPERA-3）和太阳风离子分析仪（SWIA）的数据。 ， 分别。我们研究了火星上层大气过渡区（从热层到外层）中热氧原子的动力学和传输过程。计算了超热氧原子的动能分布函数。已经显示，在火星上的质子极光事件期间，系外层充满大量的超热氧原子，其动能达到逃逸能2 eV。除光化学源外，在氧电晕中还会形成热馏分。在质子极光事件中产生了从火星大气中逸出的原子氧的非热通量。质子极光是偶发的极光事件。所以，