Intense bombardment of solar system planets in the immediate aftermath of protoplanetary disk dissipation has played a key role in their atmospheric evolution. During this epoch, energetic collisions will have removed substantial masses of gas from rocky planet atmospheres. Noble gases are powerful tracers of this early atmospheric history, xenon in particular, which on Mars and Earth shows significant depletions and isotopic fractionations relative to the lighter noble gasses. To evaluate the effect of impacts on the loss and fractionation of xenon, we measure its ionization and recombination efficiency by laser shock and apply these constraints to model impact-driven atmospheric escape on Mars. We demonstrate that impact bombardment within the first 200 to 300 million years of solar system history generates the observed Xe depletion and isotope fractionation of the modern martian atmosphere. This process may also explain the Xe depletion recorded in Earth’s deep mantle and provides a latest date for the timing of giant planet instability.

中文翻译：

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早期火星大气的冲击雕刻


在原行星盘耗散之后，太阳系行星的强烈轰炸在其大气演化中发挥了关键作用。在这个时期，高能碰撞将从岩石行星大气中带走大量气体。惰性气体是早期大气历史的有力示踪剂，尤其是氙，在火星和地球上，相对于较轻的惰性气体，氙气显示出明显的消耗和同位素分馏。为了评估撞击对氙的损失和分馏的影响，我们通过激光冲击测量了氙的电离和复合效率，并应用这些约束来模拟火星上撞击驱动的大气逃逸。我们证明，在太阳系历史的前 200 到 3 亿年中，撞击轰击产生了观察到的现代火星大气中的 Xe 消耗和同位素分馏。这个过程也可以解释地球深地幔中记录的 Xe 消耗，并为巨行星不稳定的时间提供了最新的日期。