INSAT-4A Launch and Early Orbit Phase Orbit Determination
- Paper number
IAC-06-C1.6.03
- Author
Dr. Vighnesam Narayanasetti Venkata, Indian Space Research Organisation (ISRO), India
- Coauthor
Mr. Pramod Kumar Soni, Indian Space Research Organisation (ISRO), India
- Coauthor
Mr. Anatta Sonney, Indian Space Research Organisation (ISRO), India
- Year
2006
- Abstract
ARIANE 5 GS Flight No. 169 successfully placed the 3080.1 kg INSAT-4A satellite in a (622 X 36103) km Geostationary Transfer Orbit (GTO), along with co-passenger MSG-2, a weather satellite for the European organization Eumetsat on 22 December 2005 (IST). After 3 Apogee Motor Firing (AMF) and 5 Station Acquisition (STAQ) maneuvers INSAT-4A was successfully placed at 81.5 degrees East longitude above the Indian Ocean in a GeoStationary Orbit (GSO) of (35789 X 35784) km on 3rd January 2006 to facilitate In-Orbit Testing (IOT) procedures. This paper analyses the performance of the Geostationary Orbit Determination System (ODS) employed to determine the transfer, intermediate and geostationary orbits during all the initial stages of the INSAT-4A mission. At each stage of the mission the orbit was determined using tracking data obtained over varying periods of time. The orbit solutions obtained from short arc OD’s are compared with those obtained using the longest arc OD of each stage of the initial phase of the mission. ODS consists mainly of three software packages namely ephemeris generator (EPHGEN), tracking data preprocessor (TDPP) and orbit determination program (ODP). The performance of the above three software and all the maneuvers employed to place the satellite in its intended position of 830 E longitude has been discussed below. The performance of the tracking systems employed by the INMARSAT stations at Lake Cowichan (Canada), Fucino (Italy), and Beijing (China); newly established ISTRAC tracking station at Biak (Indonesia) and the SCES-3 antenna at the INSAT Master Control Facility, Hassan, India, has also been evaluated. The orbit of the satellite had to be determined continuously at a brisk pace to a good degree of accuracy to meet the requirements of the mission operations. The main computation process of the orbit determination system is tracking data pre-processing, trajectory generation and estimation. The main features of TDPP are editing, smoothing, selection and correction of systematic, environmental errors and biases. Trajectory generation is performed through numerical integration of differential equations of motion of satellite. The force model mainly includes earth's gravitation, aerodynamic drag, luni-solar gravitational forces and solar radiation pressure. Cowell's method is used for trajectory generation. Weighted least squares technique and iterative differential correction process is used to obtain the refined state. The quality of tracking data obtained both from the INMARSAT network of external stations, BIAK station tracking data from ISTRAC network and the SCES-3 antenna at INSAT Master Control Facility, Hassan, was good. The INSAT-4A Geostationary Transfer Orbit (GTO) was determined to be (622.953 X 36102.896) km. The INSAT-4A injection parameters were within the ARIANESPACE-quoted launch vehicle dispersion (3 sigma). A notable characteristic of the INSAT-4A ODS was that, successive Apogee Motor Firing (AMF) and Station acquisition (STAQ) maneuvers planning were planned within short intervening periods. For AMF and STAQ strategies, orbits were determined using lesser duration of tracking data depending on the requirements of the mission. ODS performed consistently well during all stages and the transitional periods of the initial phase of the INSAT-4A mission.
- Abstract document
- Manuscript document
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