Polar Satellite Launch Vehicle

The Polar Satellite Launch Vehicle, commonly known by its abbreviation PSLV, is an expendable launch system developed 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, commercially available only from Russia. PSLV can also launch small size satellites into geostationary transfer orbit (GTO).^[4]

In the year 2015 alone India successfully launched 17 foreign satellites belonging to Canada, Indonesia, Singapore, United Kingdom and United States. Some notable payloads launched by PSLV include India's first lunar probe Chandrayaan-1, India's first interplanetary mission, Mangalyaan (Mars orbiter) and India's first space observatory, Astrosat.^[2]

Development

PSLV was designed and developed in the early 1990s at Vikram Sarabhai Space Centre near Thiruvananthapuram, Kerala. The inertial 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 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.^[5] After this initial setback, the PSLV successfully completed its second mission in 1994.^[6] The fourth launch of PSLV suffered a partial failure in 1997, leaving its payload in a lower than planned orbit. Since then, the PSLV has launched 24 times with no further failures.^[7]

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.^[8]

Vehicle description

The PSLV has four stages using solid and liquid propulsion systems alternately. The first stage, one of the largest solid rocket motors in the world, carries 138 tonnes of hydroxyl-terminated polybutadiene urethane-bound (HTPB) propellant and develops a maximum thrust of about 4,800 kN. The 2.8-m diameter motor case is made of maraging steel and has an empty mass of 30,200 kg.^[3] 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 nozzle to produce asymmetric thrust. The solution is stored in two cylindrical aluminium tanks strapped to the solid rocket motor and pressurised with nitrogen. Roll control is provided by two small liquid engines on opposite sides of the stage, the Roll Control Thrusters (RCT).

On the PSLV 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. In the standard PSLV, each booster carries nine tonnes of propellant and produces 510 kN thrust. The PSLV-XL uses larger boosters which carry 12 tonnes of propellant and produce 719 kN thrust. Two strap-on boosters are equipped with SITVC for additional attitude control.^[3] The PSLV-CA uses no strap-on boosters.

The second stage employs the Vikas engine and carries 41.5 tonnes (40 tonnes till C-5 mission) of liquid propellant – unsymmetrical dimethylhydrazine (UDMH) as fuel and nitrogen tetroxide (N₂O₄) as oxidiser. It generates a maximum thrust of 800 kN (724 till C-5 mission). The engine is hydraulically gimbaled (±4°) to provide pitch and yaw control, while roll control is provided by two hot gas reaction control motors.

The third stage uses 7 tonnes of HTPB-based solid propellant and produces a maximum thrust of 240 kN. 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).^[3]

The fourth stage is powered by twin engines burning monomethylhydrazine (MMH) and mixed oxides of nitrogen (MON). Each engine generates 7.4 kN 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 2,500 kg of propellant in the PSLV and PSLV-XL and 2,100 kg in the PSLV-CA.^[9]

PSLV is developed with a group of wide-range control units.

Variants

ISRO has envisaged a number of variants of PSLV to cater to different mission requirements. There are currently three operational versions of the PSLV — the standard (PSLV), the core-alone (PSLV-CA) without the six strap-on booster motors, and the (PSLV-XL) version, which carries more solid fuel in its strap-on motors than the standard version.^[10] These configurations provide wide variations in payload capabilities ranging from 3800 kg in LEO to 1800 kg in Sun-synchronous orbit.

PSLV-G (Operational)

The standard version of the PSLV (PSLV-G) has four stages using solid and liquid propulsion systems alternately and six strap-on boosters. It currently has capability to launch 1,678 kg to 622 km into Sun-synchronous orbit.

PSLV-CA (Operational)

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. Two small roll control modules and two first-stage motor control injection tanks were still attached to the side of the first stage.^[9] The fourth stage of the CA variant has 400 kg less propellant when compared to its standard version.^[9] It currently has capability to launch 1,100 kg to 622 km Sun synchronous orbit.^[11]

PSLV-XL (Operational)

PSLV-XL is the uprated version of Polar Satellite Launch Vehicle in its standard configuration boosted by more powerful, stretched strap-on boosters.^[9] Weighing 320 tonnes at lift-off, the vehicle uses larger strap-on motors (PSOM-XL) to achieve higher payload capability. PSOM-XL uses larger 1-metre diameter, 13.5m length motors, and carries 12 tonnes of solid propellants instead of 9 tonnes used in the earlier configuration of PSLV.^[12] On 29 December 2005, ISRO successfully tested the improved version of strap-on booster for the PSLV. The first version of PSLV-XL was the launch of Chandrayaan-1 by PSLV C11. The payload capability for this variant is 1800 kg compared to 1600 kg for the other variants.^[11] Other launches include the RISAT Radar Imaging Satellite and GSAT-12.^[13]

PSLV-3S (Under development / Proposed)

ISRO is also considering the development of a three-stage version of the rocket without six strap-on boosters (with the second stage of the four-stage version removed) which will be capable of placing 500 kg to LEO.^[11][14]

Launch history

As of 26 September 2016 the PSLV has made 37 launches, with 35 successfully reaching their planned orbits, one outright failure and one partial failure, yielding a success rate of 7001950000000000000♠95% (or 7001970000000000000♠97% including the partial failure). All launches have occurred from the Satish Dhawan Space Centre (SDSC), known before 2002 as the Sriharikota Range (SHAR).

Flight	Variant	Launch date/time (UTC)	Launch Pad	Payload	Payload Mass	Result
D1	PSLV-G	20 September 1993 05:12	First	IRS-1E	846 kg	Failure
	Maiden flight; attitude control failure at second stage separation.[15]
D2	PSLV-G	15 October 1994 05:05	First	IRS-P2	804 kg	Success
	[16]
D3	PSLV-G	21 March 1996 04:53	First	IRS-P3	920 kg	Success
	[17]
C1	PSLV-G	29 September 1997 04:47	First	IRS-1D	1250 kg	Partial failure
	First operational flight; fourth stage under-performed resulting in lower than planned orbit. Satellite used own propulsion to move to correct orbit.[18]
C2	PSLV-G	26 May 1999 06:22	First	Oceansat-1 DLR-Tubsat Kitsat-3	1050 kg 45 kg 107 kg	Success
	First launch to have foreign satellites, and first to carry multiple satellites.[19][20]
C3	PSLV-G	22 October 2001 04:53	First	TES PROBA BIRD	1108 kg 94 kg 92 kg	Success
	First multi-orbit mission. TES and BIRD were injected into a nominal 568 km circular sun synchronous polar orbit, PROBA was injected into a 568 X 638 km elliptical orbit. Orbit was raised using RCS thrusters on fourth stage.[21][22]
C4	PSLV-G	12 September 2002 10:23	First	MetSat-1 (Kalpana-1)	1060 kg	Success
	India's first launch to GTO. GTO payload capability has reached 1200 kg from 2002 onward, compared to 1050 kg previously. First use of lightweight carbon composite payload adapter.[23][24][25]
C5	PSLV-G	17 October 2003 04:52	First	RESOURCESAT-1 (IRS-P6)	1360 kg	Success
	Payload capability had been progressively increased by more than 600 kg since the first PSLV launch. Launch took place despite heavy rain.[26][27]
C6	PSLV-G	5 May 2005 04:45	Second	Cartosat-1 HAMSAT	1560 kg 42.5 kg	Success
	First PSLV launch from the second launch pad.[28]
C7	PSLV-G	10 January 2007 03:54	First	Cartosat-2 SRE-1 LAPAN-TUBsat PEHUENSAT-1	680 kg 500 kg 56 kg 6 kg	Success
	First flight of hardware upgrade, first launch of reentry capsule (SRE).[29]
C8	PSLV-CA	23 April 2007 10:00	Second	AGILE AAM	352 kg 185 kg	Success
	First flight of the 'Core-Alone' configuration. ISRO's first commercial launch (foreign satellite as the main payload).[30][31]
C10	PSLV-CA	21 January 2008 03:45	First	TecSAR	295 kg	Success
	ISRO's second commercial launch (foreign satellite as the main payload).[32][33]
C9	PSLV-CA	28 April 2008 03:53	Second	Cartosat-2A IMS-1/TWSAT RUBIN-8 CanX-6/NTS CanX-2 Cute-1.7+APD II Delfi-C3 SEEDS-2 COMPASS-1 AAUSAT-II	690 kg 83 kg 8 kg 6.5 kg 3.5 kg 3 kg 2.2 kg 1 kg 1 kg 0.75 kg	Success
	[34][35]
C11	PSLV-XL	22 October 2008 00:52	Second	Chandrayaan-1	1380 kg	Success
	First flight of the PSLV-XL configuration, first Indian Lunar probe.[36][37]
C12	PSLV-CA	20 April 2009 01:15	Second	RISAT-2 ANUSAT	300 kg 40 kg	Success
	India's first radar imaging satellite, RISAT.[38][39]
C14	PSLV-CA	23 September 2009 06:21	First	Oceansat-2 Rubin 9.1 Rubin 9.2 SwissCube-1 BeeSat UWE-2 ITUpSAT1	960 kg 8 kg 8 kg 1 kg 1 kg 1 kg 1 kg	Success
	Rubin 9.1 and 9.2 intentionally remained attached to the fourth stage. SwissCube-1 was the first Swiss satellite, and ITUpSAT1 was the first satellite to be constructed in Turkey.[40][41][42][43][44][45]
C15	PSLV-CA	12 July 2010 03:52	First	Cartosat-2B ALSAT-2A AISSat-1 TIsat-1 STUDSAT	694 kg 117 kg 6.5 kg 1 kg 0.95 kg	Success
	AISSat-1 and TIsat are part of NLS-6.[46][47][48][49][50][51][52]
C16	PSLV-G	20 April 2011 04:42	First	ResourceSat-2 X-Sat YouthSat	1206 kg 106 kg 92 kg	Success
	[53]
C17	PSLV-XL	15 July 2011 11:18	Second	GSAT-12	1410 kg	Success
	First use of Vikram flight computer.[54][55]
C18	PSLV-CA	12 October 2011 05:31	First	Megha-Tropiques SRMSAT Jugnu VesselSat-1	1000 kg 10.9 kg 3 kg 28.7 kg	Success
	[56][57]
C19	PSLV-XL	26 April 2012 00:17	First	RISAT-1	1850 kg	Success
	[58]
C21	PSLV-CA	9 September 2012 04:23	First	SPOT-6 mRESINS PROITERES	720 kg 50 kg 15 kg	Success
	mRESINS tested avionics for future PSLV launches. ISRO's third commercial launch (foreign satellite as the main payload). ISRO's 100th mission.[59][60]
C20	PSLV-CA	25 February 2013 12:31	First	SARAL Sapphire NEOSSat TUGSAT-1 UniBRITE-1 STRaND-1 AAUSAT3	409 kg 148 kg 74 kg 14 kg 14 kg 6.5 kg 0.8 kg	Success
	TUGSAT-1 and UniBRITE were the first Austrian satellites.[61][62][63]
C22	PSLV-XL	1 July 2013 18:11	First	IRNSS-1A	1425 kg	Success
	India's first regional navigation satellite.[64]
C25	PSLV-XL	5 November 2013 09:08	First	Mars Orbiter Mission	1350 kg	Success
	India's first Mars mission.[65][66]
C24	PSLV-XL	4 April 2014 11:44	First	IRNSS-1B	1432 kg	Success
	India's second regional navigation satellite.[67][68]
C23	PSLV-CA	30 June 2014 04:22	First	SPOT-7 CanX-4 CanX-5 AISAT VELOX-1	714 kg 15 kg 15 kg 14 kg 7 kg	Success
	ISRO's fourth commercial launch (foreign satellite as the main payload).[69]
C26	PSLV-XL	16 October 2014 20:02	First	IRNSS-1C	1425.4 kg	Success
	Seventh PSLV-XL and third Navigation Satellite launch.[70][71]
C27	PSLV-XL	28 March 2015 11:49	Second	IRNSS-1D	1425 kg	Success
	Eighth PSLV-XL and fourth Navigation Satellite launch.[72]
C28	PSLV-XL	10 July 2015 16:28	First	UK-DMC3A UK-DMC3B UK-DMC3C CBNT-1 DeOrbitSail	447 kg 447 kg 447 kg 91 kg 7 kg	Success
	At the time it was the heaviest commercial mission (1439 kg) successfully accomplished using a launch vehicle assembled by ISRO.[73][74]
C30	PSLV-XL	28 September 2015 04:30	First	Astrosat LAPAN-A2 exactView 9 Lemur-2 #1 Joel Lemur-2 #2 Peter Lemur-2 #3 Jeroen Lemur-2 #4 Chris	1650 kg 68 kg 5.5 kg 4 kg 4 kg 4 kg 4 kg	Success
	Launch of India's first dedicated multi-wavelength space observatory and ISRO's first launch of US satellites.[75]
C29	PSLV-CA	16 December 2015 12:30	First	TeLEOS-1 VELOX-C1 VELOX-II Kent Ridge-1 Galassia Athenoxat-1[76]	400 kg 123 kg 13 kg 78 kg 3.4 kg -	Success
	Commercial launch of 6 Singaporean satellites. Fourth stage re-ignition demonstrated successfully after payload deployment.[77][78][79]
C31	PSLV-XL	20 January 2016 04:01	Second	IRNSS-1E	1425 kg	Success
	IRNSS-1E, fifth navigation satellite of the seven satellites constituting the IRNSS space segment launched. It carries two types of payloads – navigation payload and ranging payload. This is the eleventh time ‘XL’ configuration is being flown.[80][81][82]
C32	PSLV-XL	10 March 2016 10:31	Second	IRNSS-1F	1425 kg	Success
	IRNSS-1F, sixth navigation satellite of the seven satellites constituting the IRNSS space segment launched. It carries two types of payloads – navigation payload and ranging payload. This is the twelfth time ‘XL’ configuration is being flown. IRNSS-1F carries Corner Cube Retro Reflectors for laser ranging.[83] Launch initially scheduled for 10:30 was delayed by one minute to avoid space debris.[84]
C33	PSLV-XL	28 April 2016 07:20	First	IRNSS-1G	1425 kg	Success
	IRNSS-1G, last navigation satellite of the seven satellites constituting the IRNSS space segment launched. India's own navigational system, the set-up for which was completed will be called NAVIC (Navigation with Indian Constellation)[85][86][87][88][89]
C34	PSLV-XL	22 June 2016 03:55	Second	Cartosat-2C LAPAN-A3 BIROS SkySat Gen2-1 GHGSat-D M3MSat Swayam SathyabamaSat 12 × Flock-2P Dove nanosatellites	727.5 kg 120 kg 130 kg 110 kg 25.5 kg 85 kg 1 kg 1.5 kg 12 × 4.7 kg	Success
	ISRO's Cartosat-2C and 19 other satellites launched.[90][91][92][93][94][95]
C35	PSLV-G	26 September 2016 03:42	First	ScatSat-1 ALSAT-2B ALSAT-1B Pathfinder-1 Pratham IIT Bombay NLS-19 ALSAT-1N PISat	371 kg 117 kg 103 kg 44 kg 10 kg 8 kg 7 kg 5.25 kg	Success
	ISRO's longest PSLV satellite launch mission. First mission of PSLV in which it launched its payloads into two different orbits.[96][97][98][99][100][101]

Planned launches

Flight	Variant	Launch date/time (UTC)	Launch Pad	Payload	Payload Mass	Result
C36	PSLV-XL	7 December 2016 04:54	First	ResourceSat-2A IITMSAT IIT Madras Max Valier Sat Venta-1 NIUSAT	1206 kg 15 kg 15 kg 7.5 kg 14.3 kg	Planned
	[102][103][104][105][106]
C37	PSLV-XL	Q1, 2017	First	EMIsat SPaDEx 81 cubesats	Total approx. 1,600 kg	Planned
	[107][108][109][110]
C38	PSLV-CA (?)	April 2017	First	Cartosat-2D Blue Diamond Green Diamond Red Diamond		Planned
	[110]
C39	PSLV-CA (?)	2017	First	Cartosat-2E		Planned
	[110]
C40?	PSLV-XL (?)	28 Dec 2017	First	TeamIndus Moon Rover		Planned

Launch Frequency

Notable flights

PSLV flight D1

This was the first developmental flight of the PSLV-D1.^[15] The IRS-1E satellite which was proposed to be launched was derived from the engineering model of IRS-1A incorporating a similar camera and an additional German-built monocular electro-optical stereo scanner. Even though the mission was a failure, the launch team and an expert committee appointed thereafter noted that the mission had validated many technologies and that most sub-systems had performed optimally.^[111][112]

PSLV flight D2

This was the second flight of PSLV program which was also its first successful flight. The vehicle carried IRS-P2 satellite which was deployed in the Sun-synchronous Low Earth orbit.

PSLV flight D3

This was the third launch of PSLV program which was also its second successful launch. The vehicle carried IRS-P3 satellite which was deployed in the Sun-synchronous Low Earth orbit.

PSLV flight C1

The launch was witnessed by the former Prime Minister I.K. Gujral and also marked India's first launch vehicle built without Russian assistance.^[113][114]

PSLV flight C2

In the flight sequence, IRS-P4 was injected first, followed by KITSAT-3 and DLR-Tubsat in that order.^[19] The mission was supported by ISTRAC network of ground stations located at Bangalore, Sriharikota, Lucknow, Mauritius, Bearslake, Russia and Biak, Indonesia. During the initial phase of the mission the ground station at Wilhem in Germany also provided network support. Upon injection of the satellites, data from the IRS-P4 was received at Hyderabad while KITSAT-3 data was received at the ground station in South Korea and the data from the DLR-Tubsat was received at the university ground station in Berlin.^[20][115]

PSLV flight C3

PSLV-C3 was the third operational launch and overall sixth mission of the PSLV program. This launch was also the forty-sixth launch by Indian Space Research Organisation since its first mission on 1 January 1962. The vehicle carried three satellites which were deployed in the Sun-synchronous Low Earth orbit.^[116][117]

PSLV flight C4

PSLV-C4 was the fourth operational launch and overall seventh mission of the PSLV program. This launch was also the forty-eight launch by Indian Space Research Organisation since its first mission on 1 January 1962. The vehicle carried and injected India's first dedicated Meteorological satellite, Kalpana-1 (originally called METSAT) into the Geosynchronous transfer orbit. PSLV-C4 was launched at 15:53 hours IST on 12 September 2002 from Satish Dhawan Space Centre (then called "Sriharikota Launching Range").^[118][119]

PSLV flight C5

PSLV-C5 was the fifth operational launch and overall eighth mission of the PSLV program. This launch was also the fifty-second launch by Indian Space Research Organisation since its first mission. The vehicle carried and injected India's remote sensing satellite, Resourcesat-1 (a.k.a IRS-P6) into the Sun-synchronous orbit. PSLV-C5 was launched at 04:52 hours Coordinated Universal Time (10:22 Indian Standard Time) on 17 October 2003 from Satish Dhawan Space Centre.^[120]

PSLV flight C6

The former President, Dr. Abdul Kalam, witnessed the launch from the Mission Control Centre.^[121] It was the first PSLV launch from second pad, using integrate-transfer-and-launch technology. After its integration in the Vehicle Assembly Building, the PSLV-C6 was transported on rails to the Umbilical Tower (UT) located one km away using the Mobile Launch Pedestal where the final operations were carried out.^[121]

PSLV flight C7

The following hardware changes^[122][123] were made since PSLV-C6:

• first use of DLA (Dual Launch Adapter) to launch 2 primary satellites in time
• reduction of propellant from 2.5 tonne to 2 tonne in the fourth liquid propellant stage
• incorporation of a video imaging system to capture payload and DLA separation events
• altitude based day of launch wind-biased steering programme during Open Loop Guidance
• removal of Secondary Injection Thrust Vector Control (SITVC) system for one of the strapons ignited in the air.

PSLV flight C9

The fourth stage first fired Cartosat-2A into orbit at an altitude of 637 km about 885 seconds after lift-off. About 45 seconds later, it propelled IMS-1 into the orbit. Then the six nano satellites belonging to a cluster called NLS-4 were injected into orbit at intervals of 20 seconds each. NLS-5, a single satellite, flew out and finally the tenth satellite Rubin-8 went along with the fourth stage into orbit. Two satellites belonged to India and the remaining were nanosatellites built by universities in different countries.^[124] This was the maximum number of satellites placed in orbit, in a single PSLV launch.^{[125][126][127]}

PSLV flight C21

Launch attended by the former Prime Minister Manmohan Singh.^[128] mRESINS (mini Redundant Strapdown Inertial Navigation System) bolted to the vehicle's fourth stage, have tested avionics for future PSLV missions.^[129]With this launch Indian Space Research Organisation marked its 100 space missions, with 62 satellites, 37 launch vehicles and 1 Space Capsule Recovery Experiment.

PSLV flight C22

Earlier launch date for PSLV C22 was fixed as 12 June 2013 (1.01AM) but the launch had been postponed because of a technical snag in the 2nd stage.^[130]

The launch of the first satellite in the Indian Regional Navigation Satellite System of the Indian Space Research Organization (ISRO), scheduled for 12 June 2013 from Sriharikota, has been postponed by 14 days after an anomaly was discovered just 11 days before launch. The satellite IRNSS-1A, which would be the first in a series of seven navigation satellites was scheduled to be launched on board the Polar Satellite Launch Vehicle (PSLV) C22 at 1.01 am on 12 June. The satellite has undergone its pre-launch checks successfully. However, ISRO said the launch vehicle had an anomaly in one electro-hydraulic control actuators. "During the electrical checks of the launch vehicle, an anomaly was observed in one of the electro-hydraulic control actuators in the second stage. It has been decided to replace this actuator," a statement by ISRO said. Officials added that the replacement of the actuator would take two weeks and it would be carried out at the launch pad and vehicle assembly area.

ISRO then replaced a faulty component in the PSLV C22 rocket and rescheduled the flight of the IRNSS-1A satellite on it for 11:41 p.m. on 1 July 2013.^[131] PSLV C22, successfully launched IRNSS-1A, the first satellite in the Indian Regional Navigation Satellite System (IRNSS).

At the completion of the countdown, PSLV C22 lifted off from the First Launch Pad at 23:41 hrs (IST) on 1 July 2013 with the ignition of the first stage and four strap-on motors of the launch vehicle.^[64]

PSLV flight C25

The Mars Orbiter Mission (MOM), informally called Mangalyaan is a Mars orbiter that was successfully injected into Earth orbit on 5 November 2013 at 2:38 PM IST (9:08 UTC) atop a PSLV-XL launch vehicle from Satish Dhawan Space Centre, Sriharikota (SHAR).

PSLV flight C29

PSLV C29 lifted off from the First Launch Pad (FLP) of SDSC SHAR at 18:00 hrs [IST] on 16 December 2015. It successfully deployed six satellites it carried with gross weight of 624 kg. After fourth stage engines were cut off primary payload TeLEOS-1 was injected in orbit at about 18 min 12 seconds after lift-off. This was followed by the deployment of other five satellites, namely Kent Ridge-1, VELOX-C1, VELOX-II, Galassia and Athenoxat-1 in quick succession in the subsequent three minutes.^[132] 67 minutes into flight fourth stage re-ignition capability was demonstrated successfully by firing its engines for duration of nearly five seconds. This capability would enable multiple satellite deployment in varying orbits on same flight.^[79]

PSLV flight C34

PSLV-C34 was launched on 22 June 2016 and successfully deployed 20 satellites in Sun-synchronous orbit. A Dual Launch Adapter with new design^[133] compared to its previous version^[134] was used to integrate all ride-sharing payloads with PS4. After completion of mission a pair of PS4 re-ignition tests were performed to reaffirm multi-orbit deployment capability of PS4.^[135] A new Inertial navigation system 'Mk IV A' employing next generation Accelerometer was introduced on this mission.^[136][137]

Launch failures

IRS-1E

On 20 September 1993 a PSLV D1, the first developmental flight rocket, failed during launch. A significant attitude disturbance occurred during second to third-stage separation, causing the attitude control command to exceed its maximum value. Because of the programming error in the pitch control loop of the digital autopilot software in the guidance and control processor, the required reversal of command polarity did not take place, causing the pitch loop to become unstable, resulted in loss of attitude control and failure to achieve orbit. The attitude control disturbance was traced to failure of one of the retro rockets designed to pull the burnt second stage away from the third stage. The vehicle crashed into the Bay of Bengal 700 seconds after take off.^[112]

IRS-1D

On 29 September 1997 a PSLV C1 rocket failed during launch. Anomalous interaction between the primary and secondary pressure regulators of the fourth stage caused a reduction in propellant flow and thrust after 250 seconds of burn time. As a result, the fourth stage was shut down by a software override timer after burning 435 seconds, before reaching the target orbit or depleting propellant. The injection velocity was 140 m/s low, resulting in an orbit of 301 x 823 km instead of the planned 817 km circular SSO.^[138] Initially, a leak of helium gas from one of the components in the fourth stage was suspected,^[113][139] similar to recent Long March 3 launch failure, but later ruled out. Resulting orbit was partially corrected using satellite's on-board thrusters, thereby raising the perigee to 737 km, while the apogee remained at 821 km.^[112]

See also

• Geosynchronous Satellite Launch Vehicle
• Geosynchronous Satellite Launch Vehicle Mk III/ LVM 3
• Comparison of orbital launchers families

Indian space programme
Indian Space Research Organisation (ISRO)
Organisations	Department of Space (DoS) Antrix Corporation Indian Institute of Space Science and Technology (IIST) Indian Institute of Remote Sensing (IIRS) Laboratory for Electro-Optics Systems (LEOS) National Atmospheric Research Laboratory (NARL) Physical Research Laboratory (PRL) Physical Research Laboratory (DECU)
Programmes	Bhaskara GAGAN GSAT INSAT IRNSS IRS Cartosat RISAT Rohini SROSS Chandrayaan Human spaceflight programme Orbital Vehicle
Spacecraft	One-off missions APPLE Aditya Aryabhata Astrosat HAMSAT IMS-1 Megha-Tropiques NISAR SARAL SAARC Satellite SRE SRE II Kalpana-1 CARE Planetary missions Chandrayaan-1 Chandrayaan-2 Mars Orbiter Mission Mangalyaan 2 Venus orbiter mission
Rockets	Orbital SLV ASLV PSLV GSLV GSLV Mk.III Suborbital Rohini ATV Concepts ULV Under development RLV-TD
Facilities	Indian Deep Space Network (IDSN) ISRO Satellite Centre (ISAC) ISRO Telemetry, Tracking and Command Network (ISTRAC) Master Control Facility (MCF) Satish Dhawan Space Centre (SDSC) Thumba Equatorial Rocket Launching Station (TERLS) ISRO Satellite Integration and Testing Establishment (ISITE)
See also	SAGA-220
List of Indian satellites List of Satish Dhawan Space Centre launches List of ISRO missions

Indian Regional Navigation Satellite System (IRNSS)
Satellites	IRNSS-1A (Jul 2013) IRNSS-1B (Apr 2014) IRNSS-1C (Oct 2014) IRNSS-1D (Mar 2015) IRNSS-1E (Jan 2016) IRNSS-1F (Mar 2016) IRNSS-1G (Apr 2016)
Related articles	Indian Space Research Organisation Polar Satellite Launch Vehicle

References

External links

Wikimedia Commons has media related to Polar Satellite Launch Vehicle.

• PSLV : Official ISRO Page
• India in Space PSLV page