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The KALPANA-1 spacecraft is providing continuity of meteorological services from the INSAT system in the Indian region. It was the first payload to be launched by ISRO's Polar Satellite Launch Vehicle (PSLV) from the Satish Dhawan Space Center, Sriharikota (SHAR), with a lift-off mass of 1055 kg, into a Geostationary Transfer Orbit (GTO). The s/c carries a 3 channel very high resolution radiometer and a weather data relay transponder. This paper describes the launch window analysis for KALPANA-1. KALPANA-1 is equipped with two earth sensors, each with two detectors mounted at +/-6.1 deg from Yaw axis in the Pitch-Yaw plane. The earth sensors (ES) provide roll and pitch data. There are three gyroscopes, mounted along each of the body axes. There is a digital sun sensor (DSS), mounted along the roll axis, which provides pitch and yaw information. The liquid apogee motor (LAM) firing is carried out with the gyros as attitude reference. The gyros are calibrated prior to the LAM firing using ES and DSS data. A method, the details of which are presented, was developed to compute the earth chord width measured by the ES and to predict the visibility times of the earth in the earth sensor field of view, as the spacecraft moves in T.O. in Roll-Sun-pointing orientation. A software, named the earth sensor scan characteristics prediction software (ESSCAN), was designed and developed incorporating the above mentioned method. The launch window over the year was generated for the spacecraft based on the mission requirement of the minimum duration of ES data for the calibration of the gyros. The earth chord width profiles were studied over the seasons and over the launch window duration. Another analysis was carried out on targeting for a higher inclination in Geosynchronous orbit and the deltav and propellant requirements were generated as a function of the launch date. For the first time in ISRO satellites, absolute sensor measurements were available for all three axes in apogee motor firing (AMF) orientation. The expected sensor readings in AMF orientations were studied from the viewpoint of verification of AMF attitude prior to the burn. KALPANA-1 was launched on September 12, 2002 by PSLV from SHAR in the designated launch window. The ES visibility predictions and earth chord width profiles generated by the ESSCAN software were used to plan the T.O. earth acquisition and gyro calibration operations. KALPANA-1 was positioned in its geostationary slot at 74 deg East after three AMF operations and three station acquisition maneuvers. Downloaded by UNIV OF CALIFORNIA SAN DIEGO on August 25, 2015 | http://arc.aiaa.org |