Apple, Google, Microsoft and Mozilla are working together in order to improve the web standards that are used across browsers...

Source: Journal of Geophysical Research: Space PhysicsThis is an authorized translation of an Eos article. 本文是Eos文章的授权翻译。近几十年来，行星科学家们已经找到了大量证据，表明在大约40亿年前的挪亚时代（Noachian），火星曾有一层相对较厚的大气层，并且表面存在液态水。从那之后，气候发生了重大变化，导致火星上的大部分大气和所有地表水消失。今天残留的火星大气是一层薄薄的包膜，主要由二氧化碳组成。如果没有一个保护性的行星磁场，这层大气也会被太阳风带走。NASA的火星大气与挥发性演化(MAVEN)航天器自2014年抵达火星以来，一直在跟踪大气中含量最丰富的离子(即原子氧和分子氧)的逃逸。在一项新研究中，Pickett等人试图将这些观测扩展到碳上，这是火星大气中第二丰富的元素。观察大气中碳(C)离子损失的一个复杂因素是，碳在质量上与占主导地位的氧(O)相近。在这项工作中，作者使用了MAVEN的超热和热离子组成仪(STATIC)收集的40个轨道数据，该仪器记录了入射离子的电荷、质量和速度。由于仪器的不确定性，STATIC记录了粒子在小质量范围内的碰撞，以给定离子的真实质量为中心分布。由于C+和O+有相似的质量，这些分布存在重叠。在确定C+的总量之前，必须对氧离子的贡献进行建模和去除。作者开发并描述了一个实现这一目标的多步骤过程。研究人员将他们的方法应用于STATIC在2018年4月收集到的数据，作为该技术的初始评估和C+逃逸率的初步近似。据估计，C+沿着磁尾以104-105 / cm²/ s的通量离开火星。这一发现与之前的模型估算的大气中的碳损失基本一致，比观察到的氧离子损失率低1-2个数量级。总的来说，STATIC在研究期间的所有观测中约有四分之一发现了可检测的C+通量。这说明，要弄清火星大气中含量最丰富的这两种成分，存在着长期的困难。了解当前大气中碳和氧的相关而又独立的故事，将是未来的一项任务，对这颗红色星球的气候历史具有影响。(Journal of...

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