Abstract. Stellar occultation observations from space can probe the stratosphere and mesosphere at a fine vertical scale around the globe unlike other measurement techniques like radiosondes, aircraft, and radio occultation. We imaged the refractive bending angle of a star centroid for a series of occultations by the atmosphere. Atmospheric refractivity, density, and then temperature are retrieved from the bending observations with the Abel transformation and Edlén's law, the hydrostatic equation, and the ideal gas law. The retrieval technique is applied to data collected by two nanosatellites operated by Terran Orbital. Measurements were primarily taken by the GEOStare SV2 mission, with a dedicated imaging telescope, supplemented with images captured by spacecraft bus sensors, namely the star trackers on other Terran Orbital missions. The bending angle noise floor is 10 arcseconds and 30 arcseconds for the star tracker and GEOStare SV2 data, respectively. The most significant sources of uncertainty are due to centroiding errors due to the fairly low-resolution stellar images and telescope pointing knowledge derived from noisy satellite attitude sensors. The former mainly affects the star tracker data, while the latter limits the GEOStare SV2 accuracy with both providing low vertical resolution. This translates to a temperature profile retrieval up to roughly 20 km for both star tracker and GEOStare SV2 datasets. In preparation of an upcoming 2023 mission designed to correct these deficiencies, SOHIP, we simulated bending angle measurements with varying magnitudes of error. The expected maximum altitude of retrieved temperature is 41 km on average for these simulated measurements with a noise floor of 0.39 arcseconds. Our work highlights the capabilities of stellar occultation observations from nanosatellites for atmospheric sounding. Future work will investigate high frequency observations of atmospheric gravity waves and turbulence, mitigating the major uncertainties observed in these datasets.

中文翻译：

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来自恒星掩星弯曲的纳米卫星观测的平流层温度测量

摘要。与无线电探空仪、飞机和无线电掩星等其他测量技术不同，来自太空的恒星掩星观测可以在全球范围内以精细的垂直尺度探测平流层和中间层。我们为一系列大气掩星拍摄了恒星质心的折射弯曲角。使用阿贝尔变换和埃德伦定律、流体静力方程和理想气体定律从弯曲观测中获取大气折射率、密度和温度。该检索技术适用于由人族轨道运营的两颗纳米卫星收集的数据。测量主要由 GEOStare SV2 任务进行，配备专用成像望远镜，并辅以航天器总线传感器捕获的图像，即其他人族轨道任务中的恒星跟踪器。恒星跟踪器和 GEOStare SV2 数据的弯曲角底噪分别为 10 角秒和 30 角秒。不确定性的最重要来源是由于相当低分辨率的恒星图像和从嘈杂的卫星姿态传感器获得的望远镜指向知识导致的质心误差。前者主要影响星跟踪器数据，而后者限制了 GEOStare SV2 的精度，两者都提供低垂直分辨率。对于恒星跟踪器和 GEOStare SV2 数据集，这转化为大约 20 公里的温度剖面检索。为了准备即将到来的 2023 年旨在纠正这些缺陷的任务 SOHIP，我们模拟了具有不同误差幅度的弯曲角度测量。对于这些模拟测量，预期的最高温度平均高度为 41 公里，本底噪声为 0.39 角秒。我们的工作突出了来自纳米卫星的恒星掩星观测用于大气探测的能力。未来的工作将研究大气重力波和湍流的高频观测，以减轻在这些数据集中观察到的主要不确定性。