Launch Vehicles

Launch Vehicles play a crucial role in the subject Technology as they are powerful machines used to carry satellites and spacecraft into space. They help in transporting payloads beyond Earth’s atmosphere, making space exploration possible.

A Launch Vehicle (Rocket) is a transportation system designed to carry a payload (satellites, spacecraft, or humans) from Earth’s surface into space. It provides the required velocity and altitude to escape Earth’s gravity. Once the rockets reach near the intended orbit, the satellites are ejected.

India has three active operational launch vehicles: Polar Satellite Launch Vehicle (PSLV), Geosynchronous Satellite Launch Vehicle (GSLV), Geosynchronous Satellite Launch Vehicle Mk-III (LVM3).

Development of Indian launch vehicles started in 1969 under Dr. Vikram Sarabhai.

Evolution of ISRO’s Launch Vehicles

India’s launch vehicle development started with Dr. Vikram Sarabhai’s vision to achieve self-reliance in space technology.

ISRO’s evolution:

Early days: Started in the 1960s with sounding rockets.
1970s: Developed SLV and ASLV launch vehicles. Launched “Aryabhata” with Soviet help.
1980s: SLV-3 made India the 7th nation to reach Earth orbit. PSLV development began.
1990s: GSLV conceived for geostationary orbit.
2000s: LVM3 development started for heavier satellites.
2010s: ISRO launched the Reusable Launch Vehicle Technology Demonstrator (RLV-TD) in February 2016
2020s: SSLV developed for small satellites. Next-Gen Launch Vehicle (NGLV) planned to replace existing rockets.

Ongoing innovation:

Reusable Launch Vehicles, Stage Recovery, VTVL, and new engines.

Sounding Rockets

Purpose:
- Probing upper atmospheric regions and conducting space research
- Testing new components for launch vehicles and satellites
Key Milestones:
- 1963: First sounding rocket launched from Thumba, Kerala (marking India’s space program’s beginning)
- 1965: ISRO started launching indigenously developed sounding rockets
- 1975: Rohini Sounding Rocket (RSR) Programme consolidated all activities

Satellite Launch Vehicle (SLV)

Initiated: 1970s
First experimental flight in 1979 (partially successful)
Successful Launch: SLV-3 (1980) – Placed Rohini Satellite (RS-1) in orbit
Key Features:
- Four-stage solid-propellant rocket
- Payload Capacity: ~40 kg
- Max Altitude: ~300 km (LEO)
Significance: Made India the 6th country with indigenous satellite launch capability.
Key Figure:Dr. APJ Abdul Kalam played a major role in SLV-3’s development.

Augmented Satellite Launch Vehicle (ASLV)

Specifications:
- Configuration: Five-stage, all-solid propellant
- Payload capacity: 150 kg (400 km circular orbit)
Objective:
- Enhance payload capacity to 150 kg (three times SLV-3)
- Validate key technologies for future launch vehicles: Strap-on technology, Inertial navigation etc.
Developmental Flights:
- March 24, 1987: First flight
- May 20, 1992 (ASLV-D3): Third flight, Successfully placed SROSS-C (106 kg).
Significance: Served as a cost-effective intermediate vehicle
- Paved the way for advanced launch vehicles like PSLV and GSLV

Polar Satellite Launch Vehicle (PSLV)

After the partial success of ASLV, ISRO needed a reliable and efficient launch vehicle for deploying Earth observation and remote sensing satellites. This led to the development of the Polar Satellite Launch Vehicle (PSLV). It was the first Indian launch vehicle to use liquid stages, providing greater control and efficiency in satellite deployment.

Why is PSLV Called the “Workhorse” of ISRO?

High Success Rate: Over 50 successful missions since 1994
Multi-Orbit & Multi-Satellite Capability
- PSLV can deploy multiple satellites in a single launch, making it highly efficient for constellation deployments.
- It has successfully carried out multi-orbit missions, where different satellites are placed in different orbits in a single launch.
First Interplanetary Launch Vehicle: Mangalyaan (Mars Orbiter Mission – 2013)
Commercial Success: Used for launching foreign satellites (Amazonia-1, Cartosat, etc.)

Key Milestones

First successful launch: October 1994
50th launch: PSLV-C48
Played a crucial role in India’s interplanetary missions:
- Chandrayaan-1 (2008): India’s first lunar probe, which confirmed the presence of water molecules on the Moon.
- Mars Orbiter Mission (Mangalyaan, 2013): India’s first mission to Mars, making India the first country to reach Mars in its maiden attempt.
Stages:Four-stage vehicle with alternating solid and liquid propulsion systems
- First Stage (PS1) – Solid Rocket Motor (S139)
  - Fuel: Hydroxyl-Terminated Polybutadiene (HTPB)
  - Strap-on Boosters: PSLV-XL uses six solid rocket strap-on boosters to provide additional thrust.
    - Other variants: PSLV-QL (four strap-ons), PSLV-DL (two strap-ons), PSLV-CA (no strap-ons).
- Second Stage (PS2) – Liquid Propellant Stage
  - Engine: Vikas Engine (Developed by Liquid Propulsion Systems Centre – LPSC)
  - Fuel: Unsymmetrical Dimethylhydrazine (UDMH)
  - Oxidizer: Nitrogen Tetroxide (N₂O₄)
- Third Stage (PS3) – Solid Propellant Stage (Motor – S7)
  - Fuel: Hydroxyl-Terminated Polybutadiene (HTPB)
- Fourth Stage (PS4) – Liquid Propellant Stage
  - Engines: Two Earth storable liquid engines.
  - Fuel: Monomethylhydrazine (MMH)
  - Oxidizer: Mixed Oxides of Nitrogen (MON)
Payload Capacity:
- Sun-Synchronous Polar Orbit (SSPO) (600 km altitude): 1,750 kg
- Sub-Geosynchronous Transfer Orbit (Sub-GTO): 1,425 kg

PSLV Variants and Launch Capabilities

Variant	Strap-on Motors	Purpose	Payload to SSPO (600 km)
PSLV-CA (“Core Alone”)	Nil	Used for lighter payloads	1,019 kg
PSLV-DL	Two	Medium-lift payloads	1,257 kg
PSLV-QL	Four	Higher payload capacity than DL	1,523 kg
PSLV-XL	Six	Highest payload capacityUsed in major missions like Chandrayaan-1 and Mars Orbiter Mission	1,750 kg

Key PSLV Missions

1. PSLV-C11 | Chandrayaan-1 (October 22, 2008)

Significance: India’s first lunar mission.
Achievements:
- Successfully placed the Chandrayaan-1 spacecraft in lunar orbit.
- Discovered water molecules on the Moon’s surface.

2. PSLV-C25 | Mars Orbiter Mission (Mangalyaan) (November 5, 2013)

Significance: India’s first interplanetary mission.
Achievements:
- Made India the first country to reach Mars orbit on its maiden attempt.
- Collected crucial data on Martian atmosphere and surface.

3. PSLV-C37 | World Record for Most Satellites in One Launch (February 15, 2017)

Significance: Set a world record for launching 104 satellites in a single mission.
Payload:
- Cartosat-2D (Indian Earth observation satellite).
- 103 co-passenger satellites, including those from the U.S., Netherlands, Israel, Kazakhstan, and Switzerland.
Impact: Established ISRO as a global leader in commercial satellite launches.

4. PSLV-C48 | 50th PSLV Flight (December 11, 2019)

Significance: Marked the 50th PSLV mission and 75th launch from Sriharikota.
Payload:
- RISAT-2BR1 (Indian radar imaging satellite).
- Nine international customer satellites launched for New Space India Ltd (NSIL).

5. PSLV-C51 | First Dedicated Commercial Launch (February 28, 2021)

Significance: First fully commercial PSLV mission by New Space India Ltd (NSIL).
Payload:
- Amazonia-1 (Brazil’s first Earth observation satellite).
- 18 additional payloads from various countries.

6. PSLV-C54/EOS-06 Mission (November 26, 2022):

Payload: The primary payload was EOS-06, an Earth observation satellite designed for oceanographic studies. The mission also carried seven commercial satellites for various international customers.
Outcome: All satellites were successfully deployed into their intended orbits. Notably, the mission utilized Orbit Change Thrusters (OCTs to adjust orbits post-launch.

7. PSLV-C55 | TeLEOS-2 Mission (April 22, 2023)

Significance: Strengthened PSLV’s reputation for precise multi-satellite deployment.
Payload:
- TeLEOS-2 (Singapore’s advanced Earth observation satellite).
- Additional co-passenger satellites.
POEM Initiative: The mission featured the PSLV Orbital Experimental Module (POEM), utilizing the spent fourth stage of the rocket as an orbital platform for scientific experiments.

8. PSLV-C57 | Aditya-L1 Mission (September 2, 2023)

Significance: India’s first solar observatory mission.
Achievements:
- Successfully carried Aditya-L1 to study the Sun’s corona and solar dynamics.
- On January 6, 2024, Aditya-L1 reached its final orbit at Lagrange Point L1, 1.5 million km from Earth.

9. PSLV-C58 | XPoSat Mission (January 1, 2024)

Significance: India’s first dedicated X-ray Polarimeter Satellite (XPoSat).
Purpose:
- Studying cosmic X-ray sources to understand high-energy astrophysical phenomena.

10. PSLV-C59 | Proba-3 Mission (December 5, 2024)

Significance: : The mission carried the Proba-3 spacecraft, a two-satellite formation flying mission developed by the European Space Agency (ESA) to study the Sun’s corona.

11. PSLV-C60 | Space Docking Experiment (SpaDeX) (December 30, 2024)

Payload: The mission included two small satellites designed to demonstrate India’s first-ever in-space docking experiment.
- Two modified IMS-1 class satellites, each weighing approximately 220 kg
Objective:Autonomous Rendezvous and Docking – Demonstrate the capability of two spacecraft to locate each other and dock autonomously in orbit.
- This technology is essential for India’s space ambitions such as Indian on Moon, sample return from the Moon, the building and operation of Bharatiya Antariksh Station (BAS), etc.
- In-space docking technology is essential when multiple rocket launches are required to achieve common mission objectives.
Docking Achievement: On January 16, 2025, the two spacecraft, designated as “Chaser” and “Target,” successfully docked, making India the fourth nation to achieve in-space docking.

Geosynchronous Satellite Launch Vehicle (GSLV)

To deploy heavier payloads into Geosynchronous Transfer Orbits (GTO), ISRO developed the Geosynchronous Satellite Launch Vehicle (GSLV) series.

Key Features of GSLV

Three-Stage Configuration:
- First Stage (GS1): Solid rocket motor (S139) with four liquid strap-on boosters (L40).
- Second Stage (GS2): Liquid fuel Vikas engine.
- Third Stage (GS3 – CUS): Cryogenic Upper Stage using liquid hydrogen (LH2) and liquid oxygen (LOX).
Payload Capacity:
- GSLV Mk I: Up to 1500 kg to GTO
- GSLV Mk II: Up to 22,50 kg to GTO and 6,000 kg to LEO.
- GSLV Mk III (LVM-3): Up to 4,000 kg to GTO and 10,000 kg to LEO.

LVM3

Launch Vehicle Mark-III (LVM3) : a three-stage medium-lift launch vehicle developed by Liquid Propulsion Systems Centre of ISRO.
Previous Name: Geosynchronous Satellite Launch Vehicle (GSLV) Mark-III
Payload Capacity:
1. Capable of placing 4 tonne class satellites of the GSAT series into Geosynchronous Transfer Orbits (GTO).
2. Can handle 8 tonne heavy payloads into Low Earth Orbits (LEO) of 600 km altitude.
Stages of LVM3:
1. First Stage: Consists of two S200 boosters strapped to the sides of the rocket body.
2. Second Stage: L110 liquid stage powered by two Vikas engines.
3. Uppermost Final Stage: Powered by a cryogenic engine. Combusts liquefied hydrogen with liquefied oxygen.
Some of the LVM 3 Missions launched are,
1. Chandrayaan-3 Mission, Chandrayaan-2 Mission
2. OneWeb India-2 Mission, OneWeb India-1 Mission
3. GSAT-29 Mission, GSAT-19 Mission, CARE Mission

Human rated LVM3 – HLVM3

The well proven and reliable heavy lift launcher LVM3 of ISRO, is identified as the launch vehicle for Gaganyaan mission.
HLVM3 will be capable of launching the Orbital Module to an intended Low Earth Orbit of 400 km.

Significance of Cryogenic Technology

Higher Efficiency: Cryogenic engines offer greater thrust compared to solid and earth-storable liquid propellant stages.
Technological Milestone: Mastery over cryogenic technology marked a significant leap, enabling ISRO to launch heavier payloads and reducing dependence on foreign launch services

Notable GSLV Missions

GSLV-D5 (2014) – First successful flight with indigenous cryogenic stage.
GSLV-F09 (2017) – Launched GSAT-9 (South Asia Satellite).
GSLV-F10 (2021, Failed) – EOS-03 (Earth Observation Satellite) launch failed due to cryogenic stage anomaly.
GSLV-F12 (2023) – Successfully launched NVS-01, the second-generation NavIC satellite.
Recent GSLV Missions
- GSLV-F14/INSAT-3DS Mission (February 17, 2024):
  - Payload: INSAT-3DS, a follow-on mission to INSAT-3DR.
  - Objective: Provide advanced meteorological services and data relay for search and rescue operations.
- GSLV-F15/NVS-02 Mission (January 29, 2025):
  - Payload: NVS-02, the second in the series of second-generation navigation satellites.
  - Objective: Further strengthen the NavIC system, providing accurate position information services.
  - Outcome: Successfully launched, marking ISRO’s 100th mission from Sriharikota and enhancing India’s autonomous satellite navigation capabilities.

Next Generation Launch Vehicle (NGLV)

NGLV will have 3 times the present payload capability with 1.5 times the cost compared to LVM3.
It will also have reusability resulting in low-cost access to space and modular green propulsion systems.
Maximum payload capability of 30 tonnes to Low Earth Orbit.
It will feature semi-cryogenic propulsion (refined kerosene as fuel with liquid oxygen as oxidiser) for the booster stages.
The development of NGLV will enable national & commercial missions including launch of human spaceflight missions to Bharatiya Antariksh Station, Lunar/inter-planetary exploration missions along with communication & earth observation satellite constellations to Low Earth Orbit.
It will be a significant step towards capability for Indian Crewed Landing on the Moon by 2040.

Small Satellite Launch Vehicle (SSLV)

3-stage Launch Vehicle.
Can launch Mini, Micro, or Nanosatellites (10 to 500 kg mass) up to 500 km in LEO.
SSLVs will cost 1/10th of a PSLV and will need only 72 hours for launch in comparison to 45 days for PSLV.
Flexibility in accommodating multiple satellites, Launch on demand feasibility, minimal launch infrastructure requirements.
Unlike the PSLV and GSLV, the SSLV can be assembled both vertically and horizontally.
Baby rocket
Kulasekarapattinam Spaceport: Foundation stone for India’s new spaceport for SSLV was laid at Kulasekarapattinam, Thoothukudi district, Tamil Nadu.

RLV-TD (Reusable Launch Vehicle – Technology Demonstrator) 2016

Fully reusable launch vehicle.
New name – Pushpak ( RLV LEX-02 MISSION )
Critical technologies – autonomous navigation, re-entry mission management.