The two leading perturbations acting on satellites in the orbital decay region of low Earth orbit are gravitational nonsphericity of the Earth and atmospheric drag. A detailed understanding of their properties is required to accurately predict satellite dynamics, such as the orbital lifetime. However, there is still room to improve current perturbation models in this region, especially for the atmosphere. The purpose of this paper is 1) to develop a simple method to reverse engineer the leading perturbations from two-line elements (TLEs), and 2) to apply the method to the 2017 Re-Entry Satellite with Gossamer Aeroshell and GPS/Iridium (EGG) nanosatellite mission as a case study. Because of the low ballistic coefficient of EGG and its low orbital altitude, flight was highly affected by both aerodynamic and geopotential effects. Secular and long-periodic effects are extracted via linearized perturbation theory. The results show that EGG acted as a low-cost passive multiphysics sensor for several phenomena, including the changing solar flux, the diurnal atmospheric bulge, rotating winds, and the zonal geopotential. For example, the second zonal geopotential harmonic coefficient is estimated to within 0.008%. To the authors’ knowledge, this is the first study to produce estimates of both atmospheric and geopotential perturbations via TLEs from a single satellite.

作用于近地轨道轨道衰减区卫星的两个主要扰动是地球引力非球面性和大气阻力。需要详细了解它们的特性才能准确预测卫星动力学，例如轨道寿命。然而，该地区目前的扰动模型仍有改进的余地，尤其是大气。本文的目的是 1) 开发一种简单的方法来逆向工程来自两线元素 (TLE) 的主要扰动，以及 2) 将该方法应用于 2017 年带有 Gossamer Aeroshell 和 GPS/Iridium 的再入卫星（ EGG) 纳米卫星任务作为案例研究。由于 EGG 的弹道系数低且轨道高度低，飞行受到空气动力学和地势效应的高度影响。通过线性化扰动理论提取长期和长周期效应。结果表明，EGG 可作为一种低成本的无源多物理场传感器，适用于多种现象，包括不断变化的太阳通量、昼夜大气膨胀、旋转风和纬向位势。例如，第二纬向位势谐波系数估计在 0.008% 以内。据作者所知，这是第一项通过来自单个卫星的 TLE 产生大气和地势扰动估计值的研究。第二纬向位势谐波系数估计在0.008%以内。据作者所知，这是第一项通过来自单个卫星的 TLE 产生大气和地势扰动估计值的研究。第二纬向位势谐波系数估计在0.008%以内。据作者所知，这是第一项通过来自单个卫星的 TLE 产生大气和地势扰动估计值的研究。