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- CartoSat-2A is a follow-up optical imaging mission of CartoSat-2 (launch Jan. 10, 2007), representing India's first dedicated military satellite (funding by the Ministry of Defense of the Government of India). The overall objective is to provide scene-specific spot imagery in high resolution to the Indian Armed Forces - which is in the process of establishing an Aerospace Command. The spacecraft and its payload, built by ISRO, is practically an identical copy of the CartoSat-2 spacecraft of ISRO. It features a lightweight and compact bus structure using the BMU (Bus Management Unit) for integrated bus functions (of the AOCS, TT&C, etc.). The spacecraft is 3-axis stabilized using high torque reaction wheels, magnetic torquers, and hydrazine thrusters. Attitude sensing is provided by a high performance star sensor and by an improved IRU (Inertial Reference Unit). The satellite is very agile providing a body-pointing capability in along-track and cross-track of up to ±45º (this supports a revisit capability of certain target regions within 4 days). Also use of the SPS (Satellite Positioning System), an 8-channel GPS receiver (C/A code) on-board for the provision of instantaneous state vectors (state vector using pseudo range and range rate measurements) for the spacecraft. The fixed solar arrays (triple-junction solar cells) provide a power of 900 W when pointed toward the sun; two NiCd batteries of 18 Ah capacity are being used for ecliptic phase bridging. CartoSat-2A has a launch mass of 690 kg and a design life of 5 years. Launch: The launch of CartoSat-2A took place on April 28, 2008 on a PSLV launcher. The launch was conducted from the Satish Dhawan Space Centre (SDSC) SHAR, Sriharikota space station in southern India. Next to the primary payload of CartoSat-2A, the PSLV-C9 vehicle successfully launched the IMS-1 (Indian Microsatellite-1) of 83 kg and eight nanosatellites for international customers. Sensor complement: PAN Camera (Panchromatic Camera). The objective is to provide imagery for cartographic applications. The optical system is designed with two mirror Ritchey-Chretien on-axis obscured reflective telescope system with a concave hyperboloidal primary mirror and convex hyperboloid secondary mirrors and the field correcting relay optics. The mirrors are made of special Zerodur glass and are light-weighted to about 60% as in CartoSat-1 series. The mirrors are mounted inside the telescope cylinder made of CFRP with special MFDs (Mirror Fixation Devices) and the whole telescope assembly is mounted to the spacecraft structure through a special suspension arrangement. The optical system is designed to provide < 1 m resolution across track. The along track GSD of < 1 m is achieved by apparent velocity reduction by a factor of 2.5. The spacecraft can be suitably biased to provide various modes of imaging:
1) Continuous strip monoscopic mode
2) Spot scene imaging (strips on either side of the ground track can be imaged)
3) Paint brush mode of imaging. This mode is used to increase the total swath. Both roll tilt and pitch tilt is employed. The PAN Camera is a nadir-pointing pushbroom CCD instrument (detector line array of 12, 288 pixels), observing in the visible spectral range of 0.5-0.85 µm with a GSD (Ground Sample Distance) of < 1 m, and a swath width of 9.6 km at nadir. The spacecraft is being monitored and controlled from the ISRO mission control center in Bangalore, India using the ISTRAC network of stations at Bangalore, Lucknow, Mauritius, Bearslake in Russia, Biak in Indonesia and Svalbard in Norway. Group: Platform_Details Entry_ID: CARTOSAT-2A Group: Platform_Identification Platform_Category: Earth Observation Satellites Short_Name: CARTOSAT-2A End_Group Group: Platform_Associated_Instruments Short_Name: PAN End_Group Group: Orbit Orbit_Altitude: 635 km Orbit_Inclination: 97.94 degrees Period: 97.4 minutes Repeat_Cycle: 4 days Perigee: 628.7 km Apogee: 653.2 km Orbit_Type: LEO > Low Earth Orbit > Polar Sun-Synchronous End_Group Creation_Date: 2008-06-27 Online_Resource: http://directory.eoportal.org/get_announce.php?an_id=10000443 Online_Resource: http://www.isro.org/pslv-c9/cartosat2a.htm Sample_Image: http://directory.eoportal.org/presentations/7336/CartoSat2A_Auto2.jpeg Group: Platform_Logistics Launch_Date: 2008-04-28 Launch_Site: Sriharikota Island, India Design_Life: 5 YEARS Primary_Sponsor: Ministry of Defense of the Government of India End_Group End_Group
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