PSLV-C11

	PSLV-C11, chosen to launch Chandrayaan-1 spacecraft, was an uprated version of ISRO's Polar Satellite Launch Vehicle standard configuration. Weighing 320 tonnes at lift-off, the vehicle used larger strap-on motors (PSOM-XL) to achieve higher payload capability. PSLV is the trusted workhorse launch Vehicle of ISRO. During September 1993- April 2008 period, PSLV had twelve consecutively successful launches carrying satellites to Sun Synchronous, Low Earth and Geosynchronous Transfer Orbits. On October 22, 2008, its fourteenth flight launched Chandrayaan-1 spacecraft.
	By mid 2008, PSLV had repeatedly proved its reliability and versatility by launching 29 satellites into a variety of orbits. Of these, ten remote sensing satellites of India, an Indian satellite for amateur radio communications, a recoverable Space Capsule (SRE-1) and fourteen satellites from abroad were put into polar Sun Synchronous Orbits (SSO) of 550-820 km heights. Besides, PSLV has launched two satellites from abroad into Low Earth Orbits of low or medium inclinations. This apart, PSLV has launched KALPANA-1, a weather satellite of India, into Geosynchronous Transfer Orbit (GTO).
	PSLV was initially designed by ISRO to place 1,000 kg class Indian Remote Sensing (IRS) satellites into 900 km polar SunSynchronous Orbits. Since the first successful flight in October 1994, the capability of PSLV was successively enhanced from 850 kg to 1,600 kg. In its ninth flight on May 5, 2005 from the Second Launch Pad (SLP), PSLV launched ISRO's remote sensing satellite,1,560 kg CARTOSAT-1 and the 42 kg Amateur Radio satellite, HAMSAT, into a 620 km polar Sun Synchronous Orbit. The improvement in the capability over successive flights has been achieved through several means. They include increased propellant loading in the stage motors, employing composite material for the satellite mounting structure and changing the sequence of firing of the strap-on motors. PSLV-C11 is 44.4 metre tall and has four stages using solid and liquid propulsion systems alternately. The first stage, carrying 138 tonne of propellant, is one of the largest solid propellant boosters in the world. Six solid propellant strap-on motors (PSOM-XL), each carrying twelve tonne of solid propellant, are strapped on to the first stage. The second stage carries 41.5 tonne of liquid propellant. The third stage uses 7.6 tonne of solid propellant and the fourth has a twin engine configuration with 2.5 tonne of liquid propellant.
	Vikram Sarabhai Space Centre (VSSC), Thiruvananthapuram, designed and developed PSLV-C11. ISRO Inertial Systems Unit (IISU) at Thiruvananthapuram developed the inertial systems for the vehicle. Liquid Propulsion Systems Centre (LPSC), also at Thiruvananthapuram, developed the liquid propulsion stages for the second and fourth stages of PSLV-C11 as well as reaction control systems. SDSC SHAR processed the solid motors and carries out launch operations. ISRO Telemetry, Tracking and Command Network (ISTRAC) provides telemetry, tracking and command support during PSLV-C11's flight.
	PSLV- C11 stages at a glance   STAGE-1 STAGE-2 STAGE-3 STAGE-4 Nomenclature Core (PSI) + Six Strap-ons (PSOM-XL) PS2 PS3 PS4 Propellant Solid HTPB Based Liquid UH25+N204  Solid HTPB based Bi-prop MMH + MON-3 Mass (Tonne) 138.0+6x12 41.5 7.6 2.5 Max Thrust 4910.0 6x720 800 246 7.31X2 Burn Time  (sec) 98 49 147 107.6 525 Stage Dia (m) 2.8 1.0 2.8 2.0 2.8 Stage Length  (m) 20.2 12.4 11.9 3.6 2.9   Control SITVC for Pitch & Yaw, Reaction Control Thrusters for Roll, SITVC in two PSOMs for Roll Control  Engine Gimball for Pitch & Yaw, Hot Gas Reaction Control Motor for Roll Control Flex Nozzle for Pitch & Yaw, PS4 RCS for Roll Engine Gimbal for pitch, Yawand Roll, on-off RCS for Coast Phase Control