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The PSLV or '''Polar Satellite Launch Vehicle''' is an Expendable Launch System operated by the Indian Space Research Organisation (ISRO). It was developed to allow India to launch its Indian Remote Sensing (IRS) satellites into Sun Synchronous Orbit s, a service that was, until the advent of the PSLV, commercially viable only from Russia . PSLV can also launch small size satellites into Geostationary Transfer Orbit (GTO). LAYOUT The PSLV has four stages using solid and liquid propulsion systems alternately. The first stage is one of the largest solid propellant boosters in the world and carries 138 metric tonnes of Hydroxyl-terminated Polybutadiene (HTPB) binded propellant with a diameter of 2.8 m. The motor case is made of Maraging Steel . The booster develops a maximum thrust of about 4,430 kN. Six strap-on motors, four of which are ignited on the ground, augment the first stage thrust. Each of these solid propellant strap-on motors carries nine metric tonne of HTPB propellant and produces 677 kN thrust. Pitch and Yaw control of the PSLV during the thrust phase of the solid motor is achieved by injection of an aqueous solution of Strontium perchlorate in the nozzle to constitute Secondary Injection Thrust Vector Control System (SITVC). The injection is stored in two cylindrical aluminum tanks strapped to the solid rocket motor and pressurized with nitrogen. SITVC in two strap-on motors is for Roll control augmentation. The second stage employs the Vikas engine and carries 41.5 metric tonne (40 metric tonne till C-5 mission) of liquid propellant — Unsymmetrical Di-Methyl Hydrazine (UDMH) as fuel and Nitrogen tetroxide (N2O4) as oxidizer. It generates a maximum thrust of 800 kN (724 till C-5 mission). Pitch & yaw control is obtained by hydraulically gimbaled engine (±4°) and two hot gas reaction control for roll. The third stage uses 7 metric tonne of HTPB-based solid propellant and produces a maximum thrust of 324 kN. It has as Kevlar-polyamide fiber case and a submerged nozzle equipped with a flex-bearing-seal gimbaled nozzle (±2°) thrust-vector engine for pitch & yaw control. For roll control it uses the RCS (Reaction Control System) of fourth stage. The fourth and the terminal stage of PSLV has a twin engine configuration using liquid propellant. With a propellant loading of 2 metric tonne (Mono-Methyl Hydrazine as fuel + Mixed Oxides of Nitrogen as oxidiser), each of these engines generates a maximum thrust of 7.4 kN. Engine is gimbaled (±3°) for pitch, yaw & roll control and for control during the coast phase uses on-off RCS. PSLV-C4 used a new lightweight carbon composite payload adapter to enables greater GTO payload capability. VARIANTS Operational ; PSLV-CA The PSLV-C8 launch used a "Core Alone" (CA) launch vehicle. This variant uses the core stages without any strap-on boosters. 1. It currently has capability to launch 1,100 kg to 622 km SSO.2 Under development / Proposed ; PSLV-XL On 29 December , 2005 , ISRO successfully tested an improved version of the strap-on booster for the PSLV. It will be used for future PSLV flights, including the launches of Chandrayaan-1 and the RISAT Radar Imaging Satellite. 3. The payload capability for this variant will be 1600 kg compared to 1450 kg for the current one 4. ; PSLV-HP As reported on the website of The New Indian Express newspaper (April 26, 2007), PSLV project director N Narayanamoorthy spoke of another version being planned called the PSLV-HP, standing for ‘high performance.’ It will have strap-ons motors, but the payload capability will be raised to 2000 kg. The HP version will be used to launch a constellation of seven navigation satellites between 2010 and 2012. Among other things, the efficiency of the stage 4 engine will be improved in this version.5. ; Three-stage PSLV ISRO is also considering the development of a three-stage version of the rocket (with the second stage of the four-stage version removed) which will be capable of placing 500 kg to LEO.678 LAUNCHES After some delays, the first launch of the PSLV occurred on 20 September 1993 . Although all main engines performed as expected, an altitude control problem was reported in the second and third stages. After this initial setback, ISRO met complete success with the third developmental launch in 1996. Further successful launches followed in 1997, 1999, and 2001. In September 2002, the 1060 kg KALPANA-1 was launched by PSLV-C4 into GTO. On 17 October 2003 , the 1360 kg Earth Observing ResourceSat1 was launched by PSLV-C5. On May 5 , 2005 , PSLV-C6 launched two satellites into orbit; CARTOSAT -I a stereoscopic Earth Observation Satellite with Cartographic applications, weighing 1560 kg, and HAMSAT providing satellite based radio service for Amateur Radio operators, weighing 42.5 kg into a high Polar Orbit (632 x 621 km). PSLV will continue be the work horse of the ISRO for its launches, especially for LEO satellites and the Chandrayaan Projects. It has undergone several improvements with each subsequent version, especially those involving thrust, efficiency and weight. On January 10 , 2007 , the PSLV-C7 carried four satellites - the 680 kg Indian remote sensing satellite CARTOSAT-2, the 550 kg Space Capsule Recovery Equipment (SRE-1) , Indonesia's LAPAN-TUBSAT (60kg) and Argentina's 6kg nanosatellite called NANO PEHUENSAT-1 into orbit. PSLV-C7 successfully lifts off On April 23 , 2007 , the PSLV-C8 carried its first commercial satellite, the Agile for the Italian Space Agency as main payload with the Advanced Avionics Module as its secondary payload Successfully {Link without Title} . This was ISRO's first purely commercial launch. All launches of foreign satellites before this had been of micro-satellites or light weight satellites piggybacked on the PSLV, with an Indian satellite being the primary payload. The PSLV-C8 was also launched without its regular 6 strap-on boosters. Another first for ISRO was the inclination of 2.5o (equatorial orbit)http://www.bharat-rakshak.com/NEWS/newsrf.php?newsid=8568http://www.outlookindia.com/pti_news.asp?gid=89, which made launch comparatively riskier than usual. LAUNCH LOG FOREIGN PAYLOADS LAUNCHED BY PSLV TRIVIA
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