Laboratory experiments for the interpretation of mass spectra from water ice particles measured in-situ onboard Cassini and future space missions

太阳系外的大部分尘埃是由水冰和嵌入的其他成分组成的。行星际航天器上的现场仪器对超高速微粒撞击进行飞行时间质谱分析。这些光谱的解释在很大程度上依赖于实验室数据。与其他化合物形成对比的是，尽管正在进行的和未来的空间飞行任务强烈需要水冰颗粒的实验室撞击光谱，但尚无法获得。在到达土星时，卡西尼号航天器上的宇宙尘埃分析仪(CDA)和离子和中性气体光谱仪(INMS)首次提供了大量来自水冰的现场数据。这两个实验都表明，光谱的出现严重依赖于撞击速度和颗粒中少量变化的非冰物质。我们提出了一个涵盖空间科学和物理化学的交叉学科计划，其中通过激光脉冲在具有不同水溶液和能量密度的水束上模拟质量谱。第一个结果表明，对于冰粒和分子以不同的速度撞击探测器，这种方法是一个很好的模拟。这些实验也适用于研究最近发现的通过电荷分离而形成的离子。与此同时，还将开发一种新的方法，利用激光的冲击波实际产生高速水滴和冰粒，然后撞击到空间探测器上使用的双胞胎探测器模型。这一结果对卡西尼号仪器和未来的空间仪器至关重要，例如对彗星和伽利略卫星。

Most of the dust in the outer solar system is made of water ice with embedded other components. In-situ instruments onboard interplanetary spacecrafts perform TOF mass spectrometry of hypervelocity micro-particle impacts. The interpretation of these spectra strongly relies on laboratory data. In contrast to other compounds, laboratory impact spectra of water ice particles are not yet available although strongly required by ongoing and future space missions. On arrival at Saturn the Cosmic Dust Analyzer (CDA) and the Ion and Neutral Gas Spectrometer (INMS) onboard the Cassini spacecraft for the first time delivered a large amount of in-situ data from water ice. Both experiments showed that the appearance of spectra depends critically on impact velocity and small amounts of varying non-icy material in the grains.We propose an interdisciplinary program, which covers space science and physical chemistry, where mass spectra are simulated by laser pulses onto a water beam with a variety of water solutions and energy densities. First results show that this method is an excellent analogue for impacts of ice particles and molecules with varying speeds onto a detector. The experiments are also suitable to investigate the recently discovered ion formation by charge separation. In parallel there will be a development of a new method, where the shock of the laser is used to actually create high velocity water droplets and ice particles, which then impact onto a twin model of the detectors used onboard space probes. The results are crucial for the Cassini instruments and future space instrumentation, e.g. to comets and the Galilean moons.