• 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.

• 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.

• 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.

• International Journal of Aeronautical and Space Sciences
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• v.8 no.1
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• pp.122-128
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• 2007

In this paper, a method of station keeping strategy using relative orbital motion and numerical optimization technique is presented for geostationary satellite. Relative position vector with respect to an ideal geostationary orbit is generated using high precision orbit propagation, and compressed in terms of polynomial and trigonometric function. Then, this relative orbit model is combined with optimization scheme to propose a very efficient and flexible method of station keeping planning. Proper selection of objective and constraint functions for optimization can yield a variety of station keeping methods improved over the classical ones. Nonlinear simulation results have been shown to support such concept.

• 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 $128.2^{\circ}E$.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.9
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• pp.75-81
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• 2003

The longitude and latitude of a geosynchronous satellite are not defined as a point in space because of various external perturbations. To perform the missions of a satellite for a communication and broadcasting, the satellite must be positioned within a predefined station keeping box in given limited space longitude. In this study, we propose east-west station keeping box larger than that of north-south station. By using the derived error equation, we verified the Koreasat station keeping box allocation by assuming one week and two weeks of station keeping cycle.

• 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.

• ETRI Journal
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• v.22 no.1
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• pp.12-19
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• 2000

Wireless communication systems using airship have been proposed in worldwide. The airship will be located at the stratosphere about $20{\sim}23\;km$ above the sea level. The position of airship will vary within the station keeping range with time due to the drag of the wind in the stratosphere. When the earth station antenna has a high gain without the tracking function, the antenna performance may be degraded by a small variation of the airship. This means that variation of airship location could result in serious degradation of the system performance. In this paper, degradation in earth station's Equivalent Isotropic Radiated Power (EIRP) and Gain to noise Temperature ratio (G/T) due to the stratospheric platform movements has been derived by calculating the deviation angle of the main beam directions between the earth station and the platform antenna. In this case, the antenna of the earth station has been assumed circular and/or patch array antennas.

• 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.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.799-804
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• 1993

In this paper, the scheme of combining the orbit correction and attitude control of a 3-axis stabilized satellite is suggested. Being coupled and complimentary, it is preferable to achieve the required orbit correction and the desired attitude control simultaneously. A solution of the probes simultaneous control of orbit correction and attitude of a satellite, is obtained by solving the two point boundary value problem numerically. The first-order gradient algorithm is used to solve the numerical problem. The simulation results show that the East-West station keeping process with the combined system of an orbit correction and an attitude control is satisfactory.