• Journal of Astronomy and Space Sciences
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• 제38권4호
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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.

• 한국항행학회논문지
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• 제28권5호
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• pp.623-631
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• 2024

현재 우리 군은 북한의 위협뿐만 아니라 다양한 전방위 위협에 신속하게 대응할 수 있는 지휘 통제 체계를 구축하기 위해 초소형위성체계 사업을 추진하고 있다. 본 논문에서는 저추력의 전기추진시스템인 홀추력기를 사용하여 초소형 군집위성 배치 형상을 획득하기 위한 비선형 제어기법을 제시한다. 제어기법은 일반적인 리야프노프(Lyapunov)의 제어 이론의 적용과 전기추진기의 on-off 제어를 위한 분석적 해법에 의해 구해지며 궤도 6요소 중 장반축만을 제어하여 위성군의 궤도 형상을 효과적으로 배치할 수 있는 기법이다. 본 연구에서 개발된 제어기법은 초소형위성체계에 적용하기위해 안정성을 검증하고 결과를 분석한다.