In this work, we simulated the atmospheric drag effect on two model SmallSats (small satellites) in low Earth orbit (LEO) with different ballistic coefficients during 1-month intervals of solar–geomagnetic quiet and perturbed conditions. The goal of this effort was to quantify how solar–geomagnetic activity influences atmospheric drag and perturbs satellite orbits, with particular emphasis on the Bastille Day event. Atmospheric drag compromises satellite operations due to increased ephemeris errors, attitude positional uncertainties and premature satellite re-entry. During a 1-month interval of generally quiescent solar–geomagnetic activity (July 2006), the decay in altitude (h) was a modest 0.53 km (0.66 km) for the satellite with the smaller (larger) ballistic coefficient of $\mathrm{2.2}\times {\mathrm{10}}^{-\mathrm{3}}$ m² kg⁻¹ ($\mathrm{3.03}\times {\mathrm{10}}^{-\mathrm{3}}$ m² kg⁻¹). The associated orbital decay rates (ODRs) during this quiet interval ranged from 13 to 23 m per day (from 16 to 29 m per day). For the disturbed interval of July 2000 the significantly increased altitude loss and range of ODRs were 2.77 km (3.09 km) and 65 to 120 m per day (78 to 142 m per day), respectively. Within the two periods, more detailed analyses over 12 d intervals of extremely quiet and disturbed conditions revealed respective orbital decays of 0.16 km (0.20 km) and 1.14 km (1.27 km) for the satellite with the smaller (larger) ballistic coefficient. In essence, the model results show that there was a 6- to 7-fold increase in the deleterious impacts of satellite drag between the quiet and disturbed periods. We also estimated the enhanced atmospheric drag effect on the satellites' parameters caused by the July 2000 Bastille Day event (in contrast to the interval of geomagnetically quiet conditions). The additional percentage increase, due to the Bastille Day event, to the monthly mean values of h and ODR are 34.69 % and 50.13 % for Sat-A and 36.45 % and 68.95 % for Sat-B. These simulations confirmed (i) the dependence of atmospheric drag force on a satellite's ballistic coefficient, and (ii) that increased solar–geomagnetic activity substantially raises the degrading effect of satellite drag. In addition, the results indicate that the impact of short-duration geomagnetic transients (such as the Bastille Day storm) can have a further deleterious effect on normal satellite operations. Thus, this work increases the visibility and contributes to the scientific knowledge surrounding the Bastille Day event and also motivates the introduction of new indices used to describe and estimate the atmospheric drag effect when comparing regimes of varying solar–geomagnetic activity. We suggest that a model of satellite drag, when combined with a high-fidelity atmospheric specification as was done here, can lead to improved satellite ephemeris estimates.

中文翻译：

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与2000年7月的巴士底日（Bastille Day）事件相比，大气对模拟低地球轨道（LEO）卫星的阻力效应与一定间隔的地磁安静条件形成鲜明对比

在这项工作中，我们在太阳-地磁安静和扰动条件下的1个月时间间隔内，模拟了两个低轨道上具有不同弹道系数的SmallSats（小型卫星）模型的大气阻力效应。这项工作的目的是量化太阳-地磁活动如何影响大气阻力和扰动卫星轨道，特别是巴士底日活动。由于增加的星历误差，姿态位置不确定性和过早的卫星重入，大气阻力损害了卫星的运行。在通常静止的1个月的太阳地磁活动时间间隔内（2006年7月），弹道系数较小（较大）的卫星的高度（h）衰减为0.53 km（0.66 km）适度。$\mathrm{2.2}\times {\mathrm{10}}^{--\mathrm{3}}$ m ² 千克^-1（$\mathrm{3.03}\times {\mathrm{10}}^{--\mathrm{3}}$ m ² 公斤^-1）。在此安静间隔期间，相关的轨道衰减率（ODR）为每天13至23 m（每天为16至29 m）。在2000年7月的扰动间隔中，海拔高度损失和ODR的范围显着增加，分别为每天2.77公里（3.09公里）和每天65至120 m（每天78至142 m）。在这两个时期内，在极为安静和受干扰条件下的12 d间隔内进行的更详细的分析显示，弹道系数较小（较大）的卫星的轨道衰减分别为0.16 km（0.20 km）和1.14 km（1.27 km）。从本质上讲，模型结果表明，在静默期和扰动期之间，卫星阻力的有害影响增加了6到7倍。我们还估计了大气阻力对卫星辐射增强的影响。由2000年7月的巴士底日事件引起的参数（与地磁静默状态的间隔形成对比）。由于巴士底日活动，额外的百分比增加至HSat-A的ODR和ODR分别为34.69％和50.13％，Sat-B的ODR为36.45％和68.95％。这些模拟证实了（i）大气阻力对卫星弹道系数的依赖性，以及（ii）太阳-地磁活动的增加大大提高了卫星阻力的降低作用。此外，结果表明，短时地磁瞬变（例如巴士底日风暴）的影响可能会对正常的卫星运行产生进一步的有害影响。因此，这项工作增加了人们的知名度，并为巴士底日活动提供了科学知识，并且在比较变化的太阳地磁活动时激发了用于描述和估算大气阻力效应的新指标。我们建议采用卫星阻力模型，