Polar Satellite Launch Vehicle and its Variants

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Enlist all the related variants and modifications here.

G - Basic; No longer in use
CA: Core alone, with roll control thruster.
modules
XL: Bigger strap on motors and payload capacity
HP: No longer mentioned at ISRO. May be replaced by NGLV program.
3S: Now called SSLV.
DL: Modified CA.
QL: Modified XL


Old photo of PSLV D1.

 

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With PSLV-C55 mission, Isro uses new rocket integration technique to cut time

NEW DELHI: Isro is gearing up for the launch of PSLV-C55 mission next week and the lift-off is likely on April 22. Unlike previous launches, this launch is unique as integration of different stages of the rocket has been done in an innovative way to help reduce time in the assembly process. The PSLV-C55 is also the first rocket to be integrated at the new PSLV Integration Facility (PIF) and is said it will put a Singaporean satellite in space.

During previous PSLV missions, the entire space vehicle was integrated at the first launchpad with the help of the Mobile Service Tower (MST). However, Isro is following a new approach with the PSLV-C55 mission as the first and second stages will be integrated at the PIF centre and will be transferred to the first launch pad via the new mobile launch pedestal (MLP).

The new approach will allow the partial integration of a PSLV vehicle even if the first launch pad has been preoccupied with another launch and thus helps increase the launch frequency and allow the space agency to launch more missions in less time.

Isro’s workhorse PSLV or Polar Satellite Launch Vehicle is the third-generation rocket. Since its first successful launch in October 1994, it has emerged as the “reliable and versatile workhorse launch vehicle”. It has till now launched about 297 customer satellites for 33 countries to the low earth orbit (LEO).

In March, Isro’s heavy-lifter LVM3-M3 launched 36 satellites of UK-headquartered OneWeb, backed by Bharti Airtel, into space and successfully placed them in orbit. The OneWeb mission was Isro's second launch of the year. In February, the space agency launched the SSLV-D2/EOS07 mission.

 

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ISRO scientists reap success with unique scientific experiment in latest PSLV mission

PTI
Synopsis
Indian Space Research Organisation (ISRO) has achieved a unique breakthrough in space technology through a successful experiment using the fourth stage of Polar Satellite Launch Vehicle (PSLV) rocket on Sunday. After placing seven Singaporean satellites into orbital slots, the scientists brought the fourth stage to a lower 300 km orbit by a controlled manoeuvre to effectively mitigate space debris that would typically last for decades and reduce the lifespan of the stage in space to just two months.

It was a double delight for scientists at ISRO on Sunday as the space agency scripted a successful mission and also reaped victory in a unique scientific experiment using the fourth stage of a PSLV rocket. In a dedicated commercial mission earlier in the day, ISRO successfully placed seven Singaporean satellites into intended orbits on board a Polar Satellite Launch Vehicle (PSLV).

During the mission, the scientists decided to perform a unique scientific experiment in which the fourth stage of the rocket would be lowered into a 300 kilometre orbit after placing customer satellites at an altitude of 536 km "to mitigate the space debris problem", according to Chairman S Somanath.

In an update after the successful launch of PSLV-C56 mission, ISRO said the unique attempt by the scientists is "successful" and "ISRO/India remains committed to reduced space debris".

According to ISRO, normally after a successful mission, a rocket before re-entering into the Earth's atmosphere would travel for "decades" in an orbit as a space debris. However, with Sunday's experiment, the duration is now reduced to "two months".

"PSLV-C56/DS-SAR Mission: The PS4 stage de-orbiting experiment is successful. The stage is purposefully manoeuvred to a 295 kms x 300 km orbit," ISRO said in a social media post.

The fourth stage of the rocket now spends significantly less time in space, reducing its duration from over decades to less than two months, before re-entering the Earth's atmosphere, ISRO said.

"Reduced time in Space = Less risk of debris. India remains committed to reduced space debris and sustainable use of space for the benefit of all," the space agency added in the social media post.

Earlier, addressing scientists from the Mission Control Centre, Somanath said: "We are going to have many exciting further activities on the PS4 stage after this (successful launch). The PSLV fourth stage, which is currently in the orbit of the satellite which is at almost 535 km circular orbit in a 5-degree inclination, will be brought back to a lower orbit of 300 km."

He said the reason for bringing back the PS4 stage to a lower orbit was "to mitigate space debris problems".

"The experiment is being done with an intent to have a lower lifespan of the stage being spent in space, primarily to make sure that the space debris mitigation problems are addressed through our conscious efforts to bring back the PSLV upper stage in a controlled manner, and to demonstrate that in this mission," Somanath, who is also Secretary, Department of Space, said.

Echoing the Chairman's view, PSLV Mission Director S R Biju said, "As our Chairman indicated, we have not completed the mission. The primary objective of the mission is completed (to place the seven Singapore satellites into intended orbits) and it has become a habit for PSLV (sic) to do some experiments (in the fourth stage of the rocket)."

"We are embarking on it after the completion of the primary mission because we are taking the PS4 stage back to another orbit, because this orbit of 536 km-570km is very much in demand for many satellites. So, we thought we will not be wandering there and we decided that we will take the PS4 stage or the spent stage to another orbit, to another objective for two purposes," he said.

"One, our chairman has told us to do whatever is best possible to mitigate the menace of debris in orbit and another thing, this precious orbit will not be occupied with spent PS4 stage as debris and we will give space for future satellites. These are two objectives with which we are doing this experiment, and that experiment is in progress," he said.

In April, ISRO undertook a similar exercise during the launch of the PSLV-C55 mission where the fourth stage of a PSLV rocket was utilised as an orbital platform to carry out scientific experiments using the PSLV Orbital Experimental Module (POEM) in the rocket.

 

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ISRO successfully conducts long-duration hot tests of Additive Manufactured Liquid Engine
May 10, 2024

ISRO achieved a major milestone with the successful hot testing of liquid rocket engine manufactured through Additive Manufacturing (AM) technology for a duration of 665 s on May 9, 2024. The engine used is the PS4 engine of PSLV upper stage.

The PS4 engine manufactured in the conventional machining and welding route has been in use for the fourth stage of PSLV which has a thrust of 7.33 kN in vacuum condition.

The same engine is also used in the Reaction Control System (RCS) of the first stage (PS1) of PSLV. The engine uses the earth-storable bipropellant combinations of Nitrogen Tetroxide as oxidizer and Mono Methyl Hydrazine as fuel in pressure-fed mode and was developed by the Liquid Propulsion Systems Centre (LPSC), ISRO.

LPSC redesigned the engine making it amenable to the Design for Additive Manufacturing (DfAM) concept thereby gaining considerable advantages. The Laser Powder Bed Fusion technique employed has brought down the number of parts from 14 to a single-piece, and eliminated 19 weld joints, saving significantly on the raw material usage per engine (13.7 kg of metal powder compared to the 565 kg of forgings and sheets for conventional manufacturing process) and reduced 60% in the overall production time. The manufacturing of the engine was done in the Indian industry (M/s WIPRO 3D), and the engine was hot tested at ISRO Propulsion Complex, Mahendragiri.

PS4 engine realized through AM route

PS4 engine during hot test

As part of the development programme, the injector head of the engine was realised and successfully hot tested earlier. Detailed flow and thermal modelling, structural simulation, and cold flow characterisation of the proto hardware were carried out to gain confidence for the hot test. Consequently, four successful developmental hot tests of integrated engine were conducted for a cumulative duration of 74 s which validated the engine performance parameters. Furthermore, the engine was successfully tested for the full qualification duration of 665 s and observed that all the performance parameters were as expected. It is planned to induct this AM PS4 engine into the regular PSLV program.

The performance of the engine during the long-duration test is shown in the following graph.

Performance parameters	Expected	Achieved
Chamber Pressure, bar	8.33±0.125	8.29
Mixture Ratio	1.40±0.05	1.37
Isp, s	307±2	307.7