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Fig. 3 | Earth, Planets and Space

Fig. 3

From: Tiangong-1’s accelerated self-spin before reentry

Fig. 3

Trajectories of the estimated angular momentum and angular velocity of Tiangong-1 in the inertia ellipsoid. The right panel shows the inertia ellipsoid of Tiangong-1. According to Euler’s kinematics equation, the angular momentum \({\varvec{H}}\) (blue) and the angular velocity \({\varvec{\omega}}\) (red) precess around one of the principal axes in the body-fixed system without external torque. The left panel presents the projections of the trajectories in the xy plane. The rings label the angles of deviation from the z-axis. Define \({L = H^2/2EI_z}\), where E is the self-spin kinetic energy. Then, the trajectories correspond to \({L = 0.9983}\). The brown line in the right panel is the polhode (the trajectory of the angular velocity) at \({L = I_y/I_z}\)

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