• Journal of Astronomy and Space Sciences
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• v.12 no.1
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• pp.102-111
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• 1995

A series of east/west and north/south station-keeping maneuvers were simulated for the KOREAST spacecraft which has to be maintained within $\pm$0.05 at the nominal longitude of $116^{\circ}$E. Weekly an biweekly based station-deeping maneuver plannings were used, and weekend maneuvers were avoided. All of the station-keeping maneuver plannings and executions were performed using KOREASTA Mission Analysis Software on VAX/VMS operating system. Fourteen weeks station-keeping maneuvers were performed and various station-keeping orbital parameters were obtained.

• Bulletin of the Korean Space Science Society
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• 2004.10b
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• pp.251-253
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• 2004

Automated east/west and north/south station-keeping maneuvers were simulated for the geostationary COMS (Communication, Ocean and Meteorological Satellite) satellite that will be launched around year 2008, The satellite has to be maintained within ${\pm}0.05^{\circ}$ at the nominal longitude of $128.2^{\circ}\;E$. The general perturbation method was used to keep the position of the geostationary satellite. Weekly based east/west and biweekly based north/south station-keeping maneuvers were investigated. The sun pointing perigee control method and two-bum strategy were used for the east/west station-keeping maneuver. Switching the right ascension of the ascending node to descending node was adopted for the north/south station-keeping maneuver. One year station-keeping maneuver was demonstrated and various station-keeping orbital parameters were analyzed.

• Proceedings of the KSRS Conference
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• v.1
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• pp.263-266
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• 2006

Now, on the developing COMS(Communication, Ocean and Meteorological Satellite) has solar panel on the South panel only. Therefore, the wheel off-loading has to be performed periodically to reduce a induced momentum energy by a asymmetric solar panel. One of two East/West station keeping maneuver to correct simultaneously longitude and eccentricity, orbit corrections may be performed during one of the two wheel off-loading manoeuvres per day to get enough observation time for meteorological and ocean sensor. In this paper, we applied a linearized orbit maneuver equation to acquire maneuver time and delta-V. Nonlinear simulation for the station keeping is performed and compared with general station keeping strategy for fuel reduction.

• Journal of Astronomy and Space Sciences
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• v.38 no.1
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• pp.65-82
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• 2021

For the vast majority of geostationary satellites currently in orbit, station keeping activities including orbit determination and maneuver planning and execution are ground-directed and dependent on the availability of ground-based satellite control personnel and facilities. However, a requirement linked to satellite autonomy and survivability in cases of interrupted ground support is often one of the stipulated provisions on the satellite platform design. It is especially important for a geostationary military-purposed satellite to remain within its designated orbital window, in order to provide reliable uninterrupted telecommunications services, in the absence of ground-based resources due to warfare or other disasters. In this paper we investigate factors affecting the robustness of a geostationary satellite's orbit in terms of the maximum duration the satellite's station keeping window can be maintained without ground intervention. By comparing simulations of orbit evolution, given different initial conditions and operations strategies, a variation of parameters study has been performed and we have analyzed which factors the duration is most sensitive to. This also provides valuable insights into which factors may be worth controlling by a military or civilian geostationary satellite operator. Our simulations show that the most beneficial factor for maximizing the time a satellite will remain in the station keeping window is the operational practice of pre-emptively loading East-West station keeping maneuvers for automatic execution on board the satellite should ground control capability be lost. The second most beneficial factor is using short station keeping maneuver cycle durations.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.9
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• pp.60-66
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• 2006

Now, on developing COMS(Communication, Ocean and Meteorological Satellite) has solar panel on the south panel only. Therefore, the wheel off-loading has to be performed periodically to reduce a induced momentum energy by a asymmetric solar panel. One of two East/West station keeping maneuver to correct simultaneously longitude and eccentricity, orbit corrections may be performed during one of the two wheel off-loading manoeuvres per day to get enough observation time for meteorological and ocean sensor. In this paper, we applied a linearized orbit maneuver equation to acquire maneuver time and delta-V. Nonlinear simulation for the station keeping is performed and compared with general station keeping strategy for fuel reduction.

• Journal of Satellite, Information and Communications
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• v.2 no.2
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• pp.16-21
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• 2007

Various perturbations by the sun, the moon and the earth itself cause a continuous change in nominal position of a geostationary satellite. In order to maintain the satellite within a required window, north-south station keeping for controlling inclination and right ascension of ascending node, and east-west station keeping for controlling eccentricity and longitude are required. In this paper, station keeping maneuver simulation for Communication, Ocean and Meteorological Satellite (COMS) was performed using COMS Flight Dynamics Software(FDS) and the results were analyzed. COMS performs weekly based east-west/north-south station keeping to maintain satellite within ${\pm}0.05^{\circ}$ at the nominal longitude of $128.2^{\circ}E$. In addition, COMS performs wheel off-loading maneuver twice a day to eliminate attitude error caused by one-solar wing in the south panel of the satellite. In this paper, station keeping maneuver considering wheel off-loading maneuver was performed and the results showed that COMS can be maintained well within ${\pm}0.05^{\circ}$ window using COMS FDS.

• Journal of Astronomy and Space Sciences
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• v.23 no.3
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• pp.245-258
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• 2006

In this paper, an automation algorithm of analyzing and scheduling the station-keeping maneuver is presented for Communication, Ocean and Meteorological Satellite (COMS). The perturbation analysis for keeping the position of the geostationary satellite is performed by analytic methods. The east/west and north/south station-keeping maneuvers we simulated for COMS. Weekly east/west and biweekly north/south station-keeping maneuvers are investigated for a period of one year. Various station-keeping orbital parameters are analyzed. As the position of COMS is not yet decided at either $128.2^{\circ}E\;or\;116.0^{\circ}E$, both cases are simulated. For the case of $128.2^{\circ}E$, east/west station-keeping requires ${\Delta}V$ of 3.50m/s and north/south station-keeping requires ${\Delta}V$ of 52.71m/s for the year 2009. For the case of $116.0^{\circ}E,\;{\Delta}V$ of 3.86m/s and ${\Delta}V$ of 52.71m/s are required for east/west and north/south station-keeping, respectively. The results show that the station-keeping maneuver of COMS is more effective at $128.2^{\circ}E$.

• Aerospace Engineering and Technology
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• v.11 no.1
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• pp.103-110
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• 2012

In the COMS satellite mission operation, more large meteorological images such as Full Disk(FD) image or 2 adjacent Extended Northern Hemisphere(ENH) images can be taken by the time shift of East West Station Keeping(EWSK) maneuver when the EWSK conflicts with the large images. In this study an analytical approach based on probability of the conflict is proposed for theoretical analysis about the EWSK time shift to avoid the conflict with FD or 2 ENH images. The EWSK time shift has been applied to the COMS operation as a test, too. The theoretical study result and test operation outcome are synthesized to provide the analysis of impact on the COMS fuel consumption by the EWSK time shift. This study is expected to contribute to the maximization of COMS meteorological mission application.

• Journal of Astronomy and Space Sciences
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• v.36 no.3
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• pp.213-223
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• 2019

This paper analyzes delta-Vs to maintain an extremely low altitude on the Moon and investigates the possibilities of performing a CubeSat mission. To formulate the station-keeping (SK) problem at an extremely low altitude, current work has utilized real-flight performance proven software, the Systems Tool Kit Astrogator by Analytical Graphics Inc. With a high-fidelity force model, properties of SK maneuver delta-Vs to maintain an extremely low altitude are successfully derived with respect to different sets of reference orbits; of different altitudes as well as deadband limits. The effect of the degree and order selection of lunar gravitational harmonics on the overall SK maneuver strategy is also analyzed. Based on the derived SK maneuver delta-V costs, the possibilities of performing a CubeSat mission are analyzed with the expected mission lifetime by applying the current flight-proven miniaturized propulsion system performances. Moreover, the lunar surface coverage as well as the orbital characteristics of a candidate reference orbit are discussed. As a result, it is concluded that an approximately 15-kg class CubeSat could maintain an orbit (30-50 km reference altitude having ${\pm}10km$ deadband limits) around the Moon for 1-6 months and provide almost full coverage of the lunar surface.

• Journal of Astronomy and Space Sciences
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• v.4 no.1
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• pp.25-33
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• 1987

For a geostationary satellite north-south keeping maneuver must control the inclination elements. The effects on the orbit plane of maneuvers and natural perturbations may be represented by a plane plot of Wc versus, Ws, since these inclination elements represent the projection of the major axis and the inclination elements are obtained.