Mechanochemical-UV generation of perchlorates and reactive nitrogen on Mars

当你用一块火石敲击另一块火石时，会产生火花。这些火花的形成是由于燧石表面上强化学键的断裂，其中一些断裂的化学键非常活泼，它们可以使空气中的联合收割机氮和氧结合形成一氧化二氮。该项目将研究火星上类似的“机械化学”反应，由风对沙尘颗粒的侵蚀驱动，可以将联合收割机微量氧气和氯化钠（食盐）结合形成高氯酸盐，并将氧气与氮气结合形成硝酸盐。高氯酸盐和硝酸盐都在火星表面被测量到。弄清楚高氯酸盐是如何形成的是很重要的，因为高氯酸盐降低了水的冰点，扩大了今天或过去火星表面或附近生命生存的区域。当加热时，它们也可以与有机分子发生反应，这可能为20世纪70年代维京海盗号着陆器任务进行的生命探测实验的一些结果提供了解释。弄清楚火星大气中的氮何时被“固定”为硝酸盐或一氧化二氮等其他形式也很重要，因为氮是（仅次于碳）生命第二重要的营养素。在今天的地球上，大气中的大部分固定氮已经被生命所固定。该项目将在实验室中模拟火星上风驱动的化学反应，并研究太阳紫外线如何影响形成的化学物质。这些结果将用于帮助解释美国航天局Cursons和Perseverance飞行任务对火星表面高氯酸盐和氮化合物的先前分析/持续分析，以及ExoMars微量气体轨道器对火星大气的持续测量。这些结果也可以用来帮助解释未来从火星返回的样品中高氯酸盐和含氮化合物的来源，以便在地球上的实验室进行更详细的分析。

When you strike a flint against another flint, you can make sparks. These sparks form due to the breaking of strong chemical bonds on the flint surfaces, and some of these broken bonds are so reactive that they can combine nitrogen and oxygen in air to form nitrous oxides. This project will investigate how similar 'mechanochemical' reactions on Mars, driven by the erosion of sand and dust particles by wind, can combine trace oxygen and sodium chloride (table salt) to form perchlorates, and oxygen with nitrogen to form nitrates. Both perchlorates and nitrates have been measured on the surface of Mars. Figuring out how perchlorates form is important, as perchlorates lower the freezing point of water and expand the areas where life could survive today, or in the past, at or near the surface of Mars. When heated, they can also react with organic molecules, potentially providing an explanation for some of the results of life detecting experiments carried out by the Viking lander missions in the 1970s. Figuring out when on Mars nitrogen in the atmosphere was 'fixed' into other forms such as nitrate or nitrous oxides is also important, as nitrogen is (after carbon) the second most important nutrient for life. On Earth today, most of the fixed nitrogen from the atmosphere has been fixed by life. This project will use experiments to mimic wind-driven chemical reactions on Mars in the laboratory, and also look at how ultraviolet rays from the sun can influence the chemicals that are formed. Results will be used to help interpret previously analysed/ongoing analyses of perchlorate and nitrogen compounds on the Martian surface by the NASA Curiosity and Perseverance missions, and ongoing measurements of the Martian atmosphere by the ExoMars Trace Gas Orbiter. The results can also be used to help interpret the origin of perchlorates and nitrogen-containing compounds in future samples returned from Mars for more detailed analyses in laboratories on Earth.