User:Gdg111/sandbox

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).

In 2015 India successfully launched 17 foreign satellites belonging to Canada, Indonesia, Singapore, the United Kingdom and the 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.

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. 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. Since then, the PSLV has launched 34 times with no further failures.

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.

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. 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. 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).

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.

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. 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. The fourth stage of the CA variant has 400 kg less propellant when compared to its standard version. It currently has capability to launch 1,100 kg to 622 km Sun synchronous orbit.


 * 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. 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. 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. Other launches include the RISAT Radar Imaging Satellite and GSAT-12.

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.
 * PSLV-3S (Under development / Proposed)

Launch history
the PSLV has made 39 launches, with 37 successfully reaching their planned orbits, one outright failure and one partial failure, yielding a success rate of (or  including the partial failure). All launches have occurred from the Satish Dhawan Space Centre (SDSC), known before 2002 as the Sriharikota Range (SHAR).

PSLV flight D1
This was the first developmental flight of the PSLV-D1. 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.

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.

PSLV flight C2
In the flight sequence, IRS-P4 was injected first, followed by KITSAT-3 and DLR-Tubsat in that order. 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.

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.

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").

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.

PSLV flight C6
The former President, Dr. Abdul Kalam, witnessed the launch from the Mission Control Centre. 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.

PSLV flight C7
The following hardware changes 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. This was the maximum number of satellites placed in orbit, in a single PSLV launch.

PSLV flight C21
Launch attended by the former Prime Minister Manmohan Singh. mRESINS (mini Redundant Strapdown Inertial Navigation System) bolted to the vehicle's fourth stage, have tested avionics for future PSLV missions. 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.

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. 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.

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. 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.

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 compared to its previous version 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. A new Inertial navigation system 'Mk IV A' employing next generation Accelerometer was introduced on this mission.

PSLV flight C36
Remote umbilical fill and drain system was used on fourth stage for the first time reducing the countdown time by one day. Experimental avionics packages were flown bolted to fourth stage including 'miniaturized advanced inertial navigation system' miniAINS, NavIC based positioning system, Vikram processor and new lithium-ion based power system. A video imaging system was also on-board, consisting of five cameras which captured and live streamed various staging events.

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.

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. Initially, a leak of helium gas from one of the components in the fourth stage was suspected, 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.