We present observations from five Mars Express (MEX) orbits in September 2016 while the spacecraft passed through the Martian induced magnetotail at altitudes up to 3,500 km. On these orbits, the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) instrument was operated in Active Ionospheric Sounding (AIS) mode at much higher altitude than normal, acting as a local sounder and detecting cold plasma structures in this region. In this paper we combine MARSIS tail measurements with solar wind data from the Solar Wind Ion Analyzer (SWIA) instrument and the Magnetometer (MAG) from Mars Atmosphere and Volatile EvolutioN (MAVEN) in order to investigate possible factors affecting plasma transport from the dayside and through the terminator. MARSIS observed structured cold ionospheric plasma along its trajectory, at all altitudes and solar zenith angles (SZAs). Isolated regions of cold plasma were also observed on each orbit as the spacecraft crossed the terminator, even at high altitudes. We conclude that the variability of plasma seen in the tail results from a multifactorial transport process, the development of which cannot be attributed to a sole parameter influencing it, despite the availability of simultaneous high quality solar wind measurements.

中文翻译：

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火星对火星磁尾中冷等离子体结构的观测

我们展示了2016年9月来自五个火星快车（MEX）轨道的观测结果，当时航天器在海拔3500公里的高度穿过火星感应磁尾。在这些轨道上，用于地下和电离层探测的火星高级雷达（MARSIS）仪器在主动电离层探测（AIS）模式下以比正常高得多的高度运行，充当本地探测仪并检测该区域的冷等离子体结构。在本文中，我们将MARSIS尾部测量结果与来自太阳风离子分析仪（SWIA）仪器的太阳风数据以及来自火星大气和挥发性挥发物（MAVEN）的磁强计（MAG）结合起来，以研究影响从白天和晚上的等离子体传输的可能因素。通过终结者。MARSIS沿其轨迹观察到结构化的电离层等离子体，在所有高度和太阳天顶角（SZA）航天器越过终结器时，即使在高空也能在每个轨道上观察到孤立的冷等离子体区域。我们得出的结论是，在尾部看到的等离子体的变异性是由多因素传输过程引起的，尽管同时进行了高质量的太阳风测量，但其发展不能归因于影响它的唯一参数。