WO2009008640A2

WO2009008640A2 - Real-time orbit determination system and method

Info

Publication number: WO2009008640A2
Application number: PCT/KR2008/003967
Authority: WO
Inventors: Yoola Hwang; Byoung-Sun Lee; Hae-Yeon Kim; Jae-Hoon Kim
Original assignee: Electronics And Telecommunications Research Institute
Priority date: 2007-07-09
Filing date: 2008-07-04
Publication date: 2009-01-15
Also published as: KR20090005634A; KR100903114B1; WO2009008640A3

Abstract

Provided is an orbit determination system and method which can determine the orbit of a geostationary satellite in real time by using observed orbit data obtained by ranging and angle-tracking which are received from a single station and by considering a wheel off-loading maneuver and a station-keeping maneuver to improve orbit determination accuracy of satellite used to process image data.

Description

REAL-TIME ORBIT DETERMINATION SYSTEM AND METHOD

TECHNICAL FIELD The present invention relates to a real-time orbit determination system and meth od for determining the orbit of a geostationary satellite in real time, and more particularl y, to a real-time orbit determination system and method for determining the orbit of a sa tellite in real time by using real-time observed orbit data obtained by ranging and angle-t racking from a single station and calculated orbit data considering a wheel off-loading m aneuver and a station-keeping maneuver for the satellite.

The present invention is supported by the Information Technology (IT) Research & Development (R&D) program of the Ministry of Information and Communication (MIC) a nd the Institute for Information Technology Advancement (IITA) [2005-S-301-03, Devel opment of Satellite Navigation Ground System and Search and Rescue Terminal Tech nologies]

BACKGROUND ART

Satellite control systems are systems that control a satellite to successfully fulfill i ts mission by receiving telemetry data from the satellite and transmitting telecommands to the satellite, and monitoring and controlling the status, orbit, and attitude of the satelli te on the ground.

To this end, satellite control systems require a computer and software in order to process and analyze data about a satellite, plan a mission, and give commands, and a n antenna or hardware in order to transmit and receive telecommands and telemetry sig nals.

Conventional satellite control systems determine the orbit of a geostationary sate llite by using ranging or angle-tracking data collected by a ground station on a 1 , 2, or 3- day basis in order to know the position of the geostationary satellite before and after sta tion-keeping. Since orbit determination systems determine the orbit of a satellite as a post-process by using data before or after fuel injection, the orbit determination systems focus on orbit accuracy, rather than fuel estimation.

In the meantime, since a geostationary communications, ocean, and meteorologi cal satellite (COMS) is equipped with a single wing, a wheel should be accelerated in or der to balance the COMS. Once the wheel is accelerated up to a limit, wheel off-loadi ng should be performed by injecting fuel twice every day in order to compensate for the acceleration. Since the wheel off-loading is performed by often injecting fuel, unlike in current geostationary satellites, velocity increment due to the wheel off-loading become s an important factor in estimating the amount of used fuel.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a geostationary satellite control system according to an embodiment of the present invention. FIG. 2 is a block diagram of a real-time orbit determination system of a flight dyn amics subsystem for the geostationary satellite control system, according to an embodi ment of the present invention.

FIG. 3 is a block diagram illustrating data flow in the real-time orbit determination system, according to an embodiment of the present invention. FIG. 4 is a flowchart illustrating a method of determining the orbit of a satellite in real time by using a real-time orbit determination system, according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL PROBLEM

The present invention provides an orbit determination system and method which can determine the orbit of a satellite in real time by using observed orbit data obtained b y ranging and angle-tracking and received from a single station.

The present invention also provides an orbit determination system and method w hich can determine the orbit of a satellite in real time by considering a wheel off-loading maneuver and a station-keeping maneuver to improve orbit determination accuracy use d to process image data.

Other objects and advantages of the present invention will become more appare nt by describing in detail exemplary embodiments thereof with reference to the attached drawings. Also, it is to be easily understood that the objects and advantages of the pr esent invention could be realized through means and combinations thereof shown in th e claims. TECHNICAL SOLUTION

Since a real-time orbit determination system and method according to the presen t invention predicts the orbit of a satellite in real time, the real-time orbit determination s ystem and method can accurately know orbit information in case of emergency. Also, the real-time orbit determination system and method can estimate the amount of injecte d fuel by estimating the position and velocity of the satellite. The real-time orbit determ ination system and method determines the orbit of a geostationary satellite by automati cally receiving short-term ranging and tracking data from a tracking, telemetry, and com mand (TTC) control and management (C&M) unit of a single station, transmitting the re ceived ranging and tracking data to an orbit determination subsystem, simultaneously e stimating in real time velocity increment due to wheel-off loading, which is performed twi ce every day, estimating position value in time due to station-keeping for a north-south ( NS) direction, which is performed once every week, and position value in time due to st ation-keeping for an east-west (EW) direction, which is performed twice every week, wh ile determining the orbit of the satellite by using the ranging and tracking data, and stori ng the position of the satellite and the estimated velocity increment in stack files.

ADVANTAGEOUS EFFECTS

Since a real-time orbit determination system and method according to the presen t invention accurately calculates the orbit of a geostationary satellite in real time by usin g real-time observed orbit data and calculated orbit data, the real-time orbit determinati on system and method can accurately know orbit information of the geostationary satelli te in case of emergency when the orbit information of the geostationary satellite used to acquire image data is necessary for meteorological observation and ocean monitoring.

The determined orbit can be used for a mission, such as photographing, becaus e the position of the geostationary satellite for a period of time necessary for the missio n can be predicted.

When a geometric singularity problem occurs because a ground station and the geostationary satellite, e.g., the communication, ocean, and meteorological satellite (C

OMS), are close to each other, the real-time orbit determination system and method ca n determine the orbit of the geostationary satellite in real time without estimating an azi muth angle bias. Since the orbit before and after fuel injection is calculated in the dete rmining of the orbit in real time, the real-time orbit determination system and method ca n accurately calculate velocity increment due to the fuel injection.

Furthermore, since fuel consumption due to the velocity increment is accurately estimated, the real-time orbit determination system and method can accurately make a next fuel injection plan and can optimally operate the satellite.

Moreover, since the observed orbit data is automatically transmitted and stored i n real time, an operator's burden to monitor and control the geostationary satellite 24 ho urs a day can be reduced.

BEST MODE

According to an aspect of the present invention, there is provided a real-time orbi t determination system comprising: a receiving unit receiving observed orbit data obtain ed by ranging and angle-tracking for a satellite at predetermined time intervals; a calcul ated orbit data generating unit generating a dynamic model by considering a wheel off-l oading maneuver and a station-keeping maneuver for the satellite, and generating calc ulated orbit data by using the dynamic model; and an orbit determining unit determining the orbit of the satellite by using a difference between the calculated orbit data and the observed orbit data at the predetermined time intervals.

According to another aspect of the present invention, there is provided a method of determining the orbit of a satellite in real time, the method comprising: receiving obse rved orbit data obtained by ranging and angle-tracking at predetermined time intervals; generating a dynamic model by considering a wheel off-loading maneuver and a station -keeping maneuver for the satellite, and generating calculated orbit data by using the dy namic model; and determining the orbit of the satellite by using a difference between th e calculated orbit data and the observed orbit data at the predetermined time intervals.

The method may further comprise storing the estimated orbit parameters in stack files, and storing a velocity increment change due to the wheel off-loading maneuver a nd a velocity increment change due to the station-keeping maneuver in report files.

Initial values of the dynamic model may be estimated orbit data obtained by the determining of the orbit of the satellite at the latest orbit determination point of time, and if there exists the wheel off-loading maneuver or the station-keeping maneuver, may c omprise estimated velocity increment due to the latest wheel off-loading maneuver or st ation-keeping maneuver. According to another aspect of the present invention, there is provided a comput er-readable recording medium having embodied thereon a program for executing the m ethod.

MODE FOR INVENTION

The present invention will now be described more fully with reference to the acco mpanying drawings, in which exemplary embodiments of the invention are shown. Alt hough the same elements are shown in different drawings, like reference numerals in th e drawings denote like elements. Detailed explanation will not be given when it is dete rmined that detailed explanation about well-known function and configuration of the pre sent invention may dilute the point of the present invention.

Unless the context dictates otherwise, the word "comprise" or variations such as "comprises" or "comprising" is understood to mean "includes, but is not limited to" such t hat other elements that are not explicitly mentioned may also be included. FIG. 1 is a block diagram of a geostationary satellite control system 100 accordin g to an embodiment of the present invention. The following explanation will be made b y exemplarily using a communication, ocean, and meteorological satellite (COMS) 200 as a geostationary satellite.

Referring to FIG. 1 , the geostationary satellite control system 100 includes an ant enna 101 , a tracking, telemetry, and command (TTC) subsystem 103, a real-time opera tions subsystem 105, a flight dynamics subsystem 107, and a mission planning subsyst em 109. The geostationary satellite control system 100 determines the orbit of the CO MS 200 by using observed orbit data obtained by ranging and angle-tracking for the sat ellite and performs a station-keeping maneuver so that the COMS 200 is kept in a nomi nal orbit.

The TTC subsystem 103 receives telemetry data through the antenna 101 from t he COMS 200, and transmits telecommand data to the COMS 200. The TTC subsyst em 103 measures a distance between the COMS 200 and the geostationary satellite co ntrol system 100, and sends commands to and monitors various types of hardware con stituting the TTC subsystem 103. The TTC subsystem 103 receives as telemetry data observed orbit data obtained by ranging and angle-tracking at 5 to 10 minute intervals, and also calculates a transponder phase of the antenna 101.

The real-time operation subsystem 105 directly controls the operation of the CO MS 200. The real-time operations subsystem 105 receives the telemetry data from the TTC subsystem 103, processes the received telemetry data so that an operator can ch eck the telemetry data, generates telecommand data, and transmits the generated telec ommand data to the COMS 200 by means of the TTC subsystem 103. The real-time o perations subsystem 105 transmits flight dynamics data among the received telemetry data to the flight dynamics subsystem 107.

The flight dynamics subsystem 107 processes the flight dynamics data, which is necessary to operate the COMS 200. The flight dynamics subsystem 107 determines the orbit of the COMS 200 by processing data observed by ranging and angle-tracking, and performs other flight dynamics functions such as event prediction, station-keeping maneuver, station relocation maneuver, fuel estimation, system management, and data base management. The flight dynamics subsystem 107 transmits information on the d etermined orbit, fuel injection, and events to the mission planning subsystem 109. In p articular, a real-time orbit determination system 200' of the flight dynamics subsystem 1 07 automatically receives the observed orbit data from the TTC subsystem 103 at prese t time intervals and stores the received observed orbit data in a designated directory. The flight dynamics subsystem 107 can more accurately determine the orbit by conside ring a wheel off-loading maneuver and a station-keeping maneuver for the COMS 200, and can minimize orbit determination error by storing estimated values obtained by the orbit determination in stack files and using the latest estimated values in determining a next orbit. The flight dynamics subsystem 107 estimates the amount of used fuel by u sing velocity increment due to the wheel off-loading maneuver and velocity increment d ue to the station-keeping maneuver and uses the estimated amount of fuel for a next fu el injection plan. The mission planning subsystem 109 makes out a schedule for a mission by rec eiving requirements for various payloads from operators and associating the requireme nts with various events. The mission planning subsystem 109 plans to give a telecom mand by using the mission, and transmits the telecommand to the real-time operations subsystem 105. The mission planning subsystem 109 receives information on the mis sion from a meteo imager (Ml) site 300 or a geostationary ocean color image (GOCI) sit e 400, and transmits information on the orbit to the Ml site 300 or the GOCI site 400 to process photographable data. FIG. 2 is a block diagram of the real-time orbit determination system 200' of the fl ight dynamics subsystem, according to an embodiment of the present invention.

Referring to FIG. 2, the real-time orbit determination system 200' includes a recei ving unit 201 , a calculated orbit data generating unit 202, an orbit determining unit 203, an orbit predicting unit 204, a system managing unit 205, a database managing unit 20 6, and a fuel calculating unit 207.

The receiving unit 201 receives observed orbit data obtained by ranging and angl e-tracking from the TTC subsystem 103 at predetermined points of time before and afte r fuel injection, and automatically stores the received observed orbit data in a designate d directory. The receiving unit 201 determines whether the received observed orbit dat a is valid, that is, whether the received observed orbit data is empty or is within a reaso nable range.

The observed orbit data may be transmitted from the TTC subsystem 103 at pre determined points of time and at time before and after fuel injection, and a transmission time interval may be short enough to determine the orbit in real time.

The calculated orbit data generating unit 202 generates a dynamic model for the COMS 200 by considering the wheel off-loading maneuver and the station-keeping man euver, and generates calculated orbit data by using the dynamic model. When the dyn amic model is generated, the Earth's gravity field, solar wind perturbation, solar-lunar p erturbation, and the existence of a wheel off-loading maneuver and a station-keeping m aneuver are considered.

Initial values of the dynamic model are estimated orbit data obtained by using ob served orbit data automatically received at the latest point of time. At this time, when t here exists a wheel off-loading maneuver and/or a station-keeping maneuver, the initial values of the dynamic model include estimated velocity increment due to the latest man euver or velocity increment calculated by telemetry. In general, wheel off-loading is pe rformed by injecting fuel twice every day, station-keeping for a north-south (NS) directio n is performed once every week, and station-keeping for east-west (EW) direction is per formed twice every week. The orbit determining unit 203 determines the current orbit of the COMS 200 in r eal time according to a control signal of the system managing unit 205. The orbit deter mining unit 203 determines the orbit of the COMS 200 by filtering a difference between the calculated orbit data generated by the calculated orbit data generating unit 202 and the observed orbit data, and estimates orbit data that is state value. The estimated or bit data, that is, estimated orbit parameters, include the position and velocity of the CO MS 200, a solar wind coefficient, and velocity increment in three axes (X, Y, and Z) due to station-keeping and wheel off-loading. During this orbit determination, a bias for the ranging and angle-tracking may be fixed on initial measurement value, or a cross-track component among the velocity increment in the three axes may be fixed and an exten ded Kalman filter may be used. The estimated orbit parameters are transmitted to the database managing unit 206, or to other sites or other subsystems by the system mana ging unit 205. The orbit predicting unit 204 predicts the orbit by using the estimated orbit param eters. The orbit predicting unit 204 generates antenna pointing data, and transmits the generated antenna pointing data to the real-time operations subsystem 105 through th e mission planning subsystem 109. The antenna 101 of the geostationary satellite con trol system 100 directly performs ranging and angle-tracking on the COMS 200 by using the antenna pointing data.

The system managing unit 205 manages the real-time orbit determination syste m 200' by checking log in-log out, whether each function is normally performed, and so on. The system managing unit 205 generates a satellite orbit determination control sig nal and transmits the generated satellite orbit determination control signal to the orbit d etermining unit 203.

The database managing unit 206 receives the estimated orbit parameters includi ng the position and velocity of the COMS 200, the solar wind coefficient, and the velocit y increment from the orbit determining unit 203 and stores the estimated orbit paramete rs in stack files according to receipt dates and times. The database managing unit 206 stores the velocity increment due to the wheel off-loading in a wheel off-loading stack f ile, the velocity increment due to the station-keeping in a station-keeping stack file, and the position and velocity of the COMS 200 and the solar wind coefficient in a real-time o rbit stack file. The stack files are used as initial values when a next orbit is determined

When storing the estimated orbit parameters in the stack files, the database man aging unit 206 also stores data related to the estimated orbit parameters in report files. That is, the database managing unit 206 stores a velocity increment change due to the wheel off-loading in a wheel off-loading report file and a velocity increment change due to the station-keeping in a station-keeping report file. The report files show a priori ch ange, a change in an estimated value due to filtering, and a sigma value, and are used i n calculating efficiency in thruster modelling.

The fuel calculating unit 207 estimates the amount of fuel used during the mane uver by using the velocity increment due to the wheel off-loading and the velocity incre ment due to the station-keeping stored in the stack files of the database managing unit 205. The estimated velocity increment among the estimated orbit parameters may be updated and used according to an operator's judgement to calculate the amount of use d fuel. The operator may compare the estimated amount of fuel with an actual amount of fuel extracted from a telemetry signal, and may directly update a corresponding repor t file according to the comparison result for the purpose of a reference when the amoun t of fuel or another mission is planned next. The operator's direct input and output ma y be performed via a graphical user interface (GUI). Although a method of determining the position of the COMS 200, evaluating the position of the COMS 200 before and after fuel injection, and estimating the amount of f uel by using the estimated velocity increment has been described above, the present in vention is not limited thereto and can be applied to a method of accumulating observed orbit data obtained by ranging and angle-tracking for a predetermined period of time an d then determining the position and velocity of the COMS 200 by considering a wheel of f-loading maneuver and a station-keeping maneuver, which is a post-process method.

FIG. 3 is a block diagram illustrating data flow in the real-time orbit determination system 200' of FIG. 2, according to an embodiment of the present invention.

Referring to FIG. 3, the receiving unit 201 receives observed orbit data obtained by ranging and angle-tracking from the TTC subsystem 103.

The calculated orbit data generating unit 202 generates calculated orbit data by using an orbit stack file, a wheel off-loading stack file, and a station-keeping stack file, which include orbit parameters estimated at the latest point of time, received from the d atabase managing unit 206 as initial values. The orbit determining unit 203 determines the orbit of the COMS 200 by using th e observed orbit data output from the receiving unit 201 and the calculated orbit data ou tput from the calculated orbit data generating unit 202. Estimated orbit values are stored in a real-time orbit stack file, velocity increment due to a wheel off-loading maneuver is stored in a wheel-off loading stack file, and vel ocity increment due to a station-keeping maneuver is stored in a station-keeping stack fi Ie. Also, a velocity increment change due to the wheel off-loading maneuver is stored i n a wheel off-loading report file, and a velocity increment change due to the station-kee ping maneuver is stored in a station-keeping report file.

The fuel calculating unit 207 estimates the amount of used fuel by using the velo city increment value due to the wheel off-loading maneuver and the velocity increment v alue due to the station-keeping maneuver. The estimated orbit information is input to the system managing unit 205 to be tr ansmitted to an external site or other subsystem, and are input to the orbit predicting un it 204 to be used for orbit prediction.

FIG. 4 is a flowchart illustrating a method of determining the orbit of a satellite in real time by a real-time orbit determination system of a flight dynamics subsystem, acco rding to an embodiment of the present invention.

Referring to FIG. 4, in operation S410, observed orbit data obtained by ranging a nd angle-tracking is received from a TTC subsystem at predetermined intervals, and is stored in a designated directory. The observed orbit data may be received at 5 to 10 minute intervals every hour which are short enough to determine the orbit in real time. In operation S420, it is determined whether the received observed orbit data is v alid. That is, it is determined whether the received observed orbit data is empty or is w ithin a reasonable range.

In operation S430, a dynamic model for the satellite is generated by considering a wheel off-loading maneuver and a station-keeping maneuver for the satellite, and calc ulated orbit data is generated by using the dynamic model. When the dynamic model i s generated, the Earth's gravity field, solar-lunar perturbation, solar wind perturbation, a nd the existence of a wheel off-loading maneuver and a station-keeping maneuver are considered.

Initial values of the dynamic model are estimated orbit data that is estimated at t he latest orbit determination point of time and stored in a stack file of a database mana ging unit. When there exists a wheel off-loading maneuver or a station-keeping mane uver, velocity increment due to wheel off-loading stored in a stack file of the database m anaging unit, and NS or EW velocity increment due to station-keeping at a correspondin g point of time are also used as the initial values.

In operation S440, whenever observed orbit data is received and there exists a w heel off-loading maneuver or a station-keeping maneuver, the orbit of the satellite is det ermined by using a difference between the calculated orbit data and the observed orbit data. That is, the orbit is determined by using an extended Kalman filter with respect t o previous estimated orbit data including the position and velocity of the satellite, a sola r wind coefficient, and velocity increment in three axes due to wheel off-loading and stat ion-keeping, to obtain estimated orbit data. During this orbit determination, a bias for t he ranging and the angle-tracking is fixed.

In operation S450, the estimated orbit parameters are stored in stack files of the database managing unit according to receipt dates and times, and a velocity increment result due to the wheel off-loading and a velocity increment result due to the station-kee ping are stored in report files. In operation S460, the amount of used fuel is estimated by using the velocity incr ement due to the wheel off-loading maneuver and the velocity increment due to the stati on-keeping maneuver. The estimated amount of fuel and an actual amount of fuel extr acted from a telemetry signal are compared with each other, and the corresponding sta ck file is updated with optimal velocity increment according to the comparison result. The present invention may be embodied as computer-readable codes on a comp uter-readable recording medium. The computer-readable recording medium is any dat a storage device that can store data which can be thereafter read by a computer syste m. Examples of the computer-readable recording medium include read-only memories (ROMs), random-access memories (RAMs), CD-ROMs, magnetic tapes, floppy disks, optical data storage devices, and carrier waves (such as data transmission through the Internet). The computer-readable recording medium can also be distributed over netw ork coupled computer systems so that the compute readable code is stored and execut ed in a distributed fashion. Functional programs, codes, and code segments for embo dying the present invention may be easily deducted by programmers in the art to which the present invention belongs.

While the present invention has been particularly shown and described with refer ence to exemplary embodiments thereof using specific terms, the embodiments and ter ms have been used to explain the present invention and should not be construed as Nm

Claims

iting the scope of the present invention defined by the claims. The preferred embodim ents should be considered in descriptive sense only and not for purposes of limitation. Therefore, the scope of the invention is defined not by the detailed description of the in vention but by the appended claims, and all differences within the scope will be constru ed as being included in the present invention.CLAIMS

1. A real-time orbit determination system comprising: a receiving unit receiving observed orbit data obtained by ranging and angle-trac king for a satellite at predetermined time intervals; a calculated orbit data generating unit generating a dynamic model by considerin g a wheel off-loading maneuver and a station-keeping maneuver for the satellite, and g enerating calculated orbit data by using the dynamic model; and an orbit determining unit determining the orbit of the satellite by using a differenc e between the calculated orbit data and the observed orbit data at the predetermined ti me intervals.

2. The real-time orbit determination system of claim 1 , wherein the receiving unit de termines whether the received observed orbit data is valid.

3.

The real-time orbit determination system of claim 1 , further comprising a databas e managing unit storing estimated orbit parameters, which are obtained by the determin ing of the obit of the satellite, in stack files.

4.

The real-time orbit determination system of claim 1 , wherein estimated orbit para meters obtained by the determining of the orbit of the satellite comprise the position an d velocity of the satellite, a solar wind coefficient, velocity increment due to the wheel of f-loading maneuver, and velocity increment due to the station-keeping maneuver.

5.

The real-time orbit determination system of claim 4, further comprising a databas e managing unit storing the estimated orbit parameters in stack files, and storing a velo city increment change due to the wheel off-loading maneuver and a velocity increment change by the station-keeping maneuver in report files.

6.

The real-time orbit determination system of claim 1 , wherein initial values of the dynamic model are estimated orbit data obtained by the determining of the orbit of the s atellite at the latest orbit determination point of time.

7.

The real-time orbit determination system of claim 1 , wherein initial values of the dynamic model are estimated orbit data obtained by the determining of the orbit of the s atellite at the latest orbit determination point of time, and if there exists the wheel off-loa ding maneuver or the station-keeping maneuver, comprise estimated velocity increment due to the latest wheel off-loading maneuver or station-keeping maneuver.

8. The real-time orbit determination system of claim 1 , further comprising a fuel calc ulating unit estimating the amount of used fuel by using estimated velocity increment du e to the wheel off-loading maneuver and estimated velocity increment due to the station -keeping maneuver which are obtained by the determining of the orbit of the satellite.

9.

A method of determining the orbit of a satellite in real time, the method comprisin g: receiving observed orbit data obtained by ranging and angle-tracking at predeter mined time intervals; generating a dynamic model by considering a wheel off-loading maneuver and a station-keeping maneuver for the satellite, and generating calculated orbit data by using the dynamic model; and determining the orbit of the satellite by using a difference between the calculated orbit data and the observed orbit data at the predetermined time intervals.

10. The method of claim 9, further comprising determining whether the received obs erved orbit data is valid, after the receiving of the observed orbit data.

11.

The method of claim 9, further comprising storing estimated orbit parameters, wh ich are obtained by the determining of the orbit of the satellite, in stack files.

12.

The method of claim 9, wherein estimated orbit parameters obtained by the deter mining of the orbit of the satellite comprise the position and velocity of the satellite, a sol ar wind coefficient, velocity increment due to the wheel off-loading maneuver, and veloc ity increment due to the station-keeping maneuver.

13.

The method of claim 12, further comprising storing the estimated orbit parameter s in stack files, and storing a velocity increment change due to the wheel off-loading ma neuver and a velocity increment change due to the station-keeping maneuver in report f iles.

14. The method of claim 9, wherein initial values of the dynamic model are estimated orbit data obtained by the determining of the orbit of the satellite at the latest orbit dete rmination point of time.

15. The method of claim 9, wherein initial values of the dynamic model are estimated orbit data obtained by the determining of the orbit of the satellite at the latest orbit dete rmination point of time, and if there exists the wheel off-loading maneuver or the station -keeping maneuver, comprise estimated velocity increment due to the latest wheel off-l oading maneuver or station-keeping maneuver.

16. The method of claim 9, further comprising estimating the amount of used fuel by using estimated velocity increment due to the wheel off-loading maneuver and estimate d velocity increment due to the station-keeping maneuver which are obtained by the det ermining of the orbit of the satellite.

17.

A computer-readable recording medium having embodied thereon a program for executing the method of claim 9.