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Choi, Jungmin,Oh, Hyungjik,Park, Chandeok,Park, Sang-Young The Korean Society for Aeronautical and Space Scie 2017 International Journal of Aeronautical and Space Sc Vol.18 No.2
This study presents the orbit determination (OD) of a candidate Korea Regional Navigation Satellite System (KRNSS) using both inter-satellite links (ISLs) and ground observations. The candidate constellation of KRNSS is first introduced. The OD algorithm based on both ISL and ground observation is developed, and consists of three main components: dynamic model for Korean navigation satellites, measurement model for ISLs and ground observations, and the batch least-square filter for estimating OD parameters. As numerical simulations are performed to analyze the OD performances, the present study focuses on investigating the effects of ISL measurements on the OD accuracy of KRNSS. Simulation results show that the use of ISLs can considerably enhance the OD accuracy to one meter (design preference) under certain distributions of ground stations.
Jungmin Choi,Hyungjik Oh,Chandeok Park,Sang-Young Park 한국항공우주학회 2017 International Journal of Aeronautical and Space Sc Vol.18 No.2
This study presents the orbit determination (OD) of a candidate Korea Regional Navigation Satellite System (KRNSS) using both inter-satellite links (ISLs) and ground observations. The candidate constellation of KRNSS is first introduced. The OD algorithm based on both ISL and ground observation is developed, and consists of three main components: dynamic model for Korean navigation satellites, measurement model for ISLs and ground observations, and the batch least-square filter for estimating OD parameters. As numerical simulations are performed to analyze the OD performances, the present study focuses on investigating the effects of ISL measurements on the OD accuracy of KRNSS. Simulation results show that the use of ISLs can considerably enhance the OD accuracy to one meter (design preference) under certain distributions of ground stations.
Precise Orbital and Geodetic Parameter Estimation using SLR Observations for ILRS AAC
Kim, Young-Rok,Park, Eunseo,Oh, Hyungjik Jay,Park, Sang-Young,Lim, Hyung-Chul,Park, Chandeok 한국우주과학회 2013 Journal of Astronomy and Space Sciences Vol.30 No.4
In this study, we present results of precise orbital geodetic parameter estimation using satellite laser ranging (SLR) observations for the International Laser Ranging Service (ILRS) associate analysis center (AAC). Using normal point observations of LAGEOS-1, LAGEOS-2, ETALON-1, and ETALON-2 in SLR consolidated laser ranging data format, the NASA/ GSFC GEODYN II and SOLVE software programs were utilized for precise orbit determination (POD) and finding solutions of a terrestrial reference frame (TRF) and Earth orientation parameters (EOPs). For POD, a weekly-based orbit determination strategy was employed to process SLR observations taken from 20 weeks in 2013. For solutions of TRF and EOPs, loosely constrained scheme was used to integrate POD results of four geodetic SLR satellites. The coordinates of 11 ILRS core sites were determined and daily polar motion and polar motion rates were estimated. The root mean square (RMS) value of post-fit residuals was used for orbit quality assessment, and both the stability of TRF and the precision of EOPs by external comparison were analyzed for verification of our solutions. Results of post-fit residuals show that the RMS of the orbits of LAGEOS-1 and LAGEOS-2 are 1.20 and 1.12 cm, and those of ETALON-1 and ETALON-2 are 1.02 and 1.11 cm, respectively. The stability analysis of TRF shows that the mean value of 3D stability of the coordinates of 11 ILRS core sites is 7.0 mm. An external comparison, with respect to International Earth rotation and Reference systems Service (IERS) 08 C04 results, shows that standard deviations of polar motion XP and YP are 0.754 milliarcseconds (mas) and 0.576 mas, respectively. Our results of precise orbital and geodetic parameter estimation are reasonable and help advance research at ILRS AAC.
박재필(Jae-Pil Park),박상영(Sang-Young Park),송영범(Young Bum Song),김극남(Guk Nam Kim),이광원(Kwangwon Lee),오형직(Hyungjik Oh),임진철(Jin-Chul Yim),이은지(EunJi Lee),황순홍(Soon-Hong Hwang),김성우(SungWoo Kim),강석주(Seok Ju Kang) 한국항공우주학회 2016 한국항공우주학회 학술발표회 논문집 Vol.2016 No.4
CANYVAL-X 임무는 분리형 우주망원경(Virtual Telescope)의 핵심기술을 두 기의 큐브위성을 이용하여 우주공간상에서 검증하는 임무이다. 분리형 우주망원경의 핵심기술은 관측 대상에 대하여 두 위성의 상대위치와 상대 자세를 동시에 일치시키는 관성 정렬(Inertial Alignment) 상태를 유지하는 것이다. CANYVAL-X 임무를 위해서는 비전 정렬 시스템을 이용한 관성 정렬 기술, 위성 간 통신을 이용한 상대궤도 결정 기술, 추력기를 이용한 상대 궤도 제어 기술, 위성 분리 기술을 임무 궤도상에서 구현 할 수 있어야 한다. 본 연구에서는 이를 위해 1 Unit (10㎝×10㎝×10㎝) 큐브위성 제리 (Jerry)와 2 Unit (10㎝×10㎝×20㎝) 큐브위성 톰 (Tom)을 개발하였고, 개발 된 두 위성의 시스템 및 성능이 임무요구조건을 만족 하는 것을 확인하였다. 또한 환경시험을 통하여 두 위성이 우주환경에서 임무를 정상적으로 수행할 수 있는 것을 확인하였다. CANYVAL-X mission is demonstrating core technology of Virtual Telescope with two CubeSats. The core technology of Virtual Telescope is consisting inertial alignment. Inertial alignment is to maintain relative position and relative attitude of two satellites with respect to target object. The mission needs to develope vision alignment system, relative orbit control with thruster, relative orbit determination with inter-satellite link system and satellite separation system. For this mission, 1 Unit (10㎝×10㎝×10㎝) CubeSat Jerry and 2 Unit (10㎝×10㎝×20㎝) Tom are developed. This study presents that the system and function of two CubeSats are satisfies mission requirements. Also, it shows that the CubeSats are able to perform the mission in space environment with the results of environment test.