PSLV C35 on launch pad
|Function||Medium lift launch system|
|Country of origin||India|
|Cost per launch||₹130 crore (US$18 million)|
-₹200 crore (US$28 million)
|Height||44 m (144 ft)|
|Diameter||2.8 m (9 ft 2 in)|
|Mass||PSLV-G: 295,000 kg (650,000 lb)|
PSLV-CA: 230,000 kg (510,000 lb)
PSLV-XL: 320,000 kg (710,000 lb)
|Payload to LEO||3,800 kg (8,400 lb)|
|Payload to SSO||1,750 kg (3,860 lb)|
|Payload to Sub-GTO||1,425 kg (3,142 lb)|
|Payload to GTO||1,200 kg (2,600 lb)|
|Notable payloads||Chandrayaan-1, Mars Orbiter Mission, Astrosat, SRE-1, NAVIC|
|Boosters (PSLV-G) – S9|
|Thrust||510 kN (110,000 lbf)|
|Specific impulse||262 s (2.57 km/s)|
|Burn time||44 seconds|
|Boosters (PSLV-XL/QL/DL) – S12|
|No. boosters||6 (XL)|
|Length||12 m (39 ft)|
|Diameter||1 m (3.3 ft)|
|Propellant mass||12,200 kg (26,900 lb) each|
|Thrust||703.5 kN (158,200 lbf) |
|Total thrust||4,221 kN (949,000 lbf) (XL) |
2,814 kN (633,000 lbf) (QL)
1,407 kN (316,000 lbf) (DL)
|Specific impulse||262 s (2.57 km/s)|
|Burn time||70 seconds |
|Length||20 m (66 ft)|
|Diameter||2.8 m (9.2 ft)|
|Propellant mass||138,200 kg (304,700 lb) each|
|Thrust||4,846.9 kN (1,089,600 lbf) |
|Specific impulse||237 s (2.32 km/s) (sea level)|
269 s (2.64 km/s) (vacuum)
|Burn time||110 seconds |
|Length||12.8 m (42 ft)|
|Diameter||2.8 m (9.2 ft)|
|Propellant mass||42,000 kg (93,000 lb) each|
|Thrust||803.7 kN (180,700 lbf) |
|Specific impulse||293 s (2.87 km/s)|
|Burn time||133 seconds |
|Length||3.6 m (12 ft)|
|Diameter||2 m (6.6 ft)|
|Propellant mass||7,600 kg (16,800 lb) each|
|Thrust||240 kN (54,000 lbf)|
|Specific impulse||295 s (2.89 km/s)|
|Burn time||83 seconds|
|Length||3 m (9.8 ft)|
|Diameter||1.3 m (4.3 ft)|
|Propellant mass||2,500 kg (5,500 lb) each|
|Engines||2 x L-2-5|
|Thrust||14.66 kN (3,300 lbf) |
|Specific impulse||308 s (3.02 km/s)|
|Burn time||425 seconds|
The Polar Satellite Launch Vehicle (PSLV) is an expendable medium-lift launch vehicle designed and 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 orbits, a service that was, until the advent of the PSLV in 1993, commercially available only from Russia. PSLV can also launch small size satellites into Geostationary Transfer Orbit (GTO).
Some notable payloads launched by PSLV include India's first lunar probe Chandrayaan-1, India's first interplanetary mission, Mars Orbiter Mission (Mangalyaan) and India's first space observatory, Astrosat.
PSLV has gained credence as a leading provider of rideshare services for small satellites, due its numerous multi-satellite deployment campaigns with auxiliary payloads usually ride sharing along an Indian primary payload. As of December 2019, PSLV has launched 319 foreign satellites from 33 countries. Most notable among these was the launch of PSLV C37 on 15 February 2017, successfully deploying 104 satellites in sun-synchronous orbit, tripling the previous record held by Russia for the highest number of satellites sent to space on a single launch.
Studies to develop a vehicle capable of delivering 600 kg payload to 550 km Sun-synchronous orbit from SHAR began in 1978. Among 35 proposed configurations, four were picked and by November 1980, a vehicle configuration with two strap-ons on a core booster (S80) with 80 tonne solid propellant loading each, a liquid stage with 30 tonne propellant load (L30) and an upper stage called Perigee-Apogee System (PAS) was being considered.
By 1981, confidence grew in remote sensing spacecraft development with launch of Bhaskara-1 and the PSLV project objectives were upgraded to have vehicle deliver 1000 kg payload in 900 km SSO. As technology transfer of Viking rocket engine firmed up, a new lighter configuration shifting away from relying on three large solid boosters was proposed by team led by APJ Abdul Kalam and eventually selected. Funding was approved in July 1982 for finalized design employing a single large S125 solid core as first stage with six 9 tonne strap-ons (S9) derived from SLV-3 first stage, liquid fueled second stage (L33) and two solid upper stages S7 and S2. This configuration needed further improvement to meet the orbital injection accuracy requirements of IRS satellites and hence solid terminal stage (S2) was replaced with a pressure fed liquid fueled stage (L1.8 or LUS) powered by twin engines derived from roll control engines of first stage. Apart from increasing precision, liquid upper stage also absorbed any deviation in performance of solid third stage. Final configuration of PSLV D1 to fly in 1993 was (6 × S9 + S125) + L37.5 + S7 + L2.
The inertial navigation systems are developed by ISRO Inertial Systems Unit (IISU) at Thiruvananthapuram. The liquid propulsion stages for the second and fourth stages of PSLV as well as the Reaction control systems (RCS) are developed by the Liquid Propulsion Systems Centre (LPSC) at Mahendragiri near Tirunelveli, Tamil Nadu. The solid propellant motors are processed at Satish Dhawan Space Centre (SHAR) at Sriharikota, Andhra Pradesh which also carries out launch operations.
The PSLV was first launched on 20 September 1993. The first and second stages performed as expected, but an attitude control problem led to the collision of the second and third stages at separation, and the payload failed to reach orbit. After this initial setback, the PSLV successfully completed its second mission in 1994. The fourth launch of PSLV suffered a partial failure in 1997, leaving its payload in a lower than planned orbit. By Nov 2014 the PSLV had launched 34 times with no further failures. (Although launch 41: August 2017 PSLV-C39 was unsuccessful.)
PSLV continues to support Indian and foreign satellite launches especially for low Earth orbit (LEO) satellites. It has undergone several improvements with each subsequent version, especially those involving thrust, efficiency as well as weight. In November 2013, it was used to launch the Mars Orbiter Mission, India's first interplanetary probe.
ISRO is planning to privatise the operations of PSLV and will work through a joint venture with private industries. The integration and launch will be managed an industrial consortium through Antrix Corporation.
The PSLV has four stages using solid and liquid propulsion systems alternately.
The first stage, one of the largest solid rocket boosters in the world, carries 138 t (304,000 lb) tonnes of hydroxyl-terminated polybutadiene-bound (HTPB) propellant and develops a maximum thrust of about 4,800 kilonewtons (1,100,000 lbf). The 2.8 m (9 ft 2 in) diameter motor case is made of maraging steel and has an empty mass of 30,200 kilograms (66,600 lb).
Pitch and yaw control during first stage flight is provided by the Secondary Injection Thrust Vector Control System (SITVC), which injects an aqueous solution of strontium perchlorate into the S139 exhaust divergent from a ring of 24 injection ports to produce asymmetric thrust. The solution is stored in two cylindrical aluminium tanks strapped to the core solid rocket motor and pressurised with nitrogen. Underneath these two SITVC tanks, Roll Control Thruster (RCT) modules with small bi-propellant (MMH/MON) liquid engine are also attached.
On the PSLV-G and PSLV-XL, first stage thrust is augmented by six strap-on solid boosters. Four boosters are ground-lit and the remaining two ignite 25 seconds after launch. The solid boosters carry 9 t (20,000 lb) or 12 t (26,000 lb) (for PSLV-XL configuration) propellant and produce 510 kN (110,000 lbf) and 719 kN (162,000 lbf) thrust respectively. Two strap-on boosters are equipped with SITVC for additional attitude control. The PSLV-CA uses no strap-on boosters.
First stage separation is aided by four pairs of retro-rockets installed on inter-stage (1/2L). During staging, these eight rockets help push away the spent stage away from second stage.
The second stage is powered by a single Vikas engine and carries 41.5 t (91,000 lb) of Earth store-able liquid propellant – unsymmetrical dimethylhydrazine (UDMH) as fuel and nitrogen tetroxide (N2O4) as oxidiser in two tanks separated by a common bulkhead. It generates a maximum thrust of 800 kN (180,000 lbf). The engine is gimbaled (±4°) in two planes to provide pitch and yaw control by two actuators, while roll control is provided by a Hot gas Reaction Control Motor (HRCM) that ejects hot gases diverted from gas generator of Vikas engine.
On inter-stage (1/2U) of PS2 there are two pairs of ullage rockets to maintain positive acceleration during PS1/PS2 staging and also two pairs of retro-rockets to help push away spent stage during PS2/PS3 staging.
The third stage uses 7 t (15,000 lb) of hydroxyl-terminated polybutadiene-based solid propellant and produces a maximum thrust of 240 kN (54,000 lbf). It has a Kevlar-polyamide fibre case and a submerged nozzle equipped with a flex-bearing-seal gimbaled nozzle (±2°) thrust vector engine for pitch & yaw control. Roll control is provided by the fourth stage reaction control system (RCS) during thrust phase as well as during combined-coasting phase.
The fourth stage is powered by regeneratively cooled twin engines, burning monomethylhydrazine (MMH) and mixed oxides of nitrogen (MON). Each engine generates 7.4 kN (1,700 lbf) thrust and is gimbaled (±3°) to provide pitch, yaw & roll control during powered flight. Coast phase attitude control is provided by RCS. The stage carries up to 2,500 kg (5,500 lb) of propellant in the PSLV and PSLV-XL and 2,100 kg (4,600 lb) in the PSLV-CA.
PS4 has carried hosted payloads like AAM on PSLV-C8, Rubin 9.1/ Rubin 9.2 on PSLV-C14 and mRESINS on PSLV-C21. But now PS4 is being augmented to serve as a long duration orbital platform after completion of primary mission. PS4 Orbital Platform (PS4-OP) will have its own power supply, telemetry package, data storage and attitude control for hosted payloads.
PSLV-C44 was the first campaign where PS4 functioned as independent orbital platform for short duration as there was no on-board power generation capacity. It carried KalamSAT-V2 as a fixed payload, a 1U cubesat by Space Kidz India based on Interorbital Systems kit.
On PSLV-C45 campaign the fourth stage had its own power generation capability as it was augmented with an array of fixed solar cells around PS4 propellant tank. Three payloads hosted on PS4-OP were, Advanced Retarding Potential Analyzer for Ionospheric Studies (ARIS 101F) by IIST, experimental AIS payload by ISRO and AISAT by Satellize.
Payload fairing of PSLV, also referred as its 'Heatshield' weighs 1,182 kg and has 3.2 meter diameter. It has isogrid construction and is made out of 7075 aluminum alloy with a 3 mm thick steel nose cap. The two halves of fairing are separated using a pyrotechnic device based jettisoning system consisting horizontal and vertical separation mechanisms.
|Stage 1||Stage 2||Stage 3||Stage 4|
|Pitch||SITVC||Engine Gimbal||Nozzle Flex||Engine Gimbal|
|Yaw||SITVC||Engine Gimbal||Nozzle Flex||Engine Gimbal|
|Roll||RCT and SITVC in 2 PSOMs||HRCM Hot Gas Reaction Control Motor||PS4 RCS||PS4 RCS|
ISRO has envisaged a number of variants of PSLV to cater to different mission requirements. There are currently two operational versions of the PSLV — the core-alone (PSLV-CA) without strap-on motors, and the (PSLV-XL) version, with six extended length (XL) strap-on motors carrying 12 tonnes of HTPB based propellant each. These configurations provide wide variations in payload capabilities up to 3,800 kg (8,400 lb) in LEO and 1,800 kg (4,000 lb) in sun-synchronous orbit.
The standard or "Generic" version of the PSLV, PSLV-G had four stages using solid and liquid propulsion systems alternately and six strap-on motors (PSOM or S9) with 9 tonne propellant loading. It had capability to launch 1,678 kg (3,699 lb) to 622 km (386 mi) into sun-synchronous orbit. PSLV-C35 was the last operational launch of PSLV-G before its discontinuation.
The PSLV-CA, CA meaning "Core Alone", model premiered on 23 April 2007. The CA model does not include the six strap-on boosters used by the PSLV standard variant but two SITVC tanks with Roll Control Thruster modules are still attached to the side of the first stage with addition of two cylindrical aerodynamic stabilizers. The fourth stage of the CA variant has 400 kg (880 lb) less propellant when compared to its standard version. It currently has capability to launch 1,100 kg (2,400 lb) to 622 km (386 mi) Sun synchronous orbit.
PSLV-XL is the upgraded version of Polar Satellite Launch Vehicle in its standard configuration boosted by more powerful, stretched strap-on boosters with 12 tonne propellant load. Weighing 320 t (710,000 lb) at lift-off, the vehicle uses larger strap-on motors (PSOM-XL or S12) to achieve higher payload capability. On 29 December 2005, ISRO successfully tested the improved version of strap-on booster for the PSLV. The first use of PSLV-XL was the launch of Chandrayaan-1 by PSLV C11. The payload capability for this variant is 1,800 kg (4,000 lb) to SSO.
PSLV-DL variant has only two strap-on boosters with 12 tonne propellant load on them. PSLV-C44 on 24 January 2019 was the first flight to use PSLV-DL variant of Polar Satellite Launch Vehicle.
PSLV-QL variant has four ground-lit strap-on boosters, each with 12 tonnes of propellant. PSLV-C45 on 1 April 2019 was the first flight of PSLV-QL.
PSLV-3S was conceived as a three-staged version of PSLV with its six strap-on boosters and second liquid stage removed. The total lift-off mass of PSLV-3S was expected to be 175 tonnes with capacity to place 500 kg in 550 km low Earth orbit.
As of 11 December 2019[update] the PSLV has made 50 launches, with 47 successfully reaching their planned orbits, two outright failures and one partial failure, yielding a success rate of 94% (or 96% including the partial failure). All launches have occurred from the Satish Dhawan Space Centre, known before 2002 as the Sriharikota Range (SHAR).
|PSLV-CA (Core Alone)||14||14||0||0|
|Total as of December 2019[update]||50||47||2||1|
About a year later, an important change was made, with the solid fourth stage being substituted by a liquid stage. This change was considered necessary since the accuracy with which the IRS satellites had to be put into orbit — within 15 km in terms of orbital height and within 0.1 degree of the desired orbital inclination — could not be achieved with a solid stage.
Today, the PSLV is available in three configurations — the generic vehicle with six strap-ons, which is the earlier edition of PSLV (which will be discontinued soon)
Currently, two versions of PSLV are operational, namely PSLV-XL (with six extended version of Strap-on motors) and the PSLV Core-alone (without Strap-on motors).
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