• Journal of Astronomy and Space Sciences
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• v.38 no.4
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• pp.217-227
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• 2021

In this study, we describe an analytical process for designing a low Earth orbit constellation for discontinuous regional coverage, to be used for a surveillance and reconnaissance space mission. The objective of this study was to configure a satellite constellation that targeted multiple areas near the Korean Peninsula. The constellation design forms part of a discontinuous regional coverage problem with a minimum revisit time. We first introduced an optimal inclination search algorithm to calculate the orbital inclination that maximizes the geometrical coverage of single or multiple ground targets. The common ground track (CGT) constellation pattern with a repeating period of one nodal day was then used to construct the rest of the orbital elements of the constellation. Combining these results, we present an analytical design process that users can directly apply to their own situation. For Seoul, for example, 39.0° was determined as the optimal orbital inclination, and the maximum and average revisit times were 58.1 min and 27.9 min for a 20-satellite constellation, and 42.5 min and 19.7 min for a 30-satellite CGT constellation, respectively. This study also compares the revisit times of the proposed method with those of a traditional Walker-Delta constellation under three inclination conditions: optimal inclination, restricted inclination by launch trajectories from the Korean Peninsula, and inclination for the sun-synchronous orbit. A comparison showed that the CGT constellation had the shortest revisit times with a non-optimal inclination condition. The results of this analysis can serve as a reference for determining the appropriate constellation pattern for a given inclination condition.

• Journal of Advanced Navigation Technology
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• v.28 no.5
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• pp.623-631
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• 2024

Currently, the Korean military is promoting a small satellite system project to establish a command and control system that can quickly respond to various threats from all directions, not only from North Korea. In this paper, we present a nonlinear control law to acquire the geometry of a small cluster satellite deployment using a low-thrust electric propulsion system, the Hall thruster. The control law is obtained by applying the general Lyapunov's control theory and analytical solution for the on-off control of the electric thruster, and it is a technique that can effectively deploy the orbital configuration of the satellite constellation by controlling only the semi-major axis of the six elements of the orbit. In this study, the stability of the developed control law is verified and the results are analyzed for application to a very small satellite system.