• 한국항공우주학회지
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• 제42권10호
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• pp.823-832
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• 2014

변위 비케플러 궤도란 질량중심이 궤도면에 대하여 변위를 갖는 궤도인데, 일반적인 궤도에 비해 다양한 임무를 수행할 수 있다는 장점이 있다. 비케플러 궤도를 유지하기 위해서는 지속적인 추력이 필요한데, 태양돛 우주선은 연료 소모 없이 지속적으로 추력을 얻을 수 있기 때문에 비케플러 궤도 운용에 적합하다. 본 논문에서는 소모성 추진제와 태양돛에 모두 적용할 수 있는 비케플러 궤도 이론을 소개하고, 태양돛 우주선에 적용시 차이점을 분석하였다. 비케플러 궤도를 4가지 유형으로 분류하고 궤도 유지를 위한 요구가속도를 계산하였다. 각 유형별 궤도안정성 식을 분석하고 시뮬레이션을 통해 검증하였다. 불안정 영역에서 궤도를 제어하기 위해 실시간 LQR을 적용한 제어기법을 개발하여 이에 대한 시뮬레이션을 수행하였다.

• Journal of Astronomy and Space Sciences
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• 제28권1호
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• pp.37-54
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• 2011

Two semi-analytic solutions for a perturbed two-body problem known as Lagrange planetary equations (LPE) were compared to a numerical integration of the equation of motion with same perturbation force. To avoid the critical conditions inherited from the configuration of LPE, non-singular orbital elements (EOE) had been introduced. In this study, two types of orbital elements, classical Keplerian orbital elements (COE) and EOE were used for the solution of the LPE. The effectiveness of EOE and the discrepancy between EOE and COE were investigated by using several near critical conditions. The near one revolution, one day, and seven days evolutions of each orbital element described in LPE with COE and EOE were analyzed by comparing it with the directly converted orbital elements from the numerically integrated state vector in Cartesian coordinate. As a result, LPE with EOE has an advantage in long term calculation over LPE with COE in case of relatively small eccentricity.

• Journal of Astronomy and Space Sciences
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• 제20권4호
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• pp.319-326
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• 2003

The motion of each satellite in a tethered satellite system is non-Keplerian in the Earth's gravitational field. In this paper, the tether perturbation force is formulated and compared with the perturbation force due to the Earth's oblateness. Also, the center of mass motion of the tethered satellite system is analyzed. The tether perturbing force on the one of satellites in a tethered satellite system is much bigger than the Earth's oblateness perturbation. The two-body motion approximation of the center of mass is acceptable to describe the motion of the system, when the libration is small.