Launch Vehicle Technology

LAUNCH VEHICLE TECHNOLOGY

Launchers or Launch Vehicles are used to carry spacecraft to space. Launch Vehicles are of two types-

Overview of ISRO’s Launch Vehicles

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

• The Small Satellite Launch Vehicle (SSLV), Human Rated Launch Vehicle (HRLV) under the Mission Gaganyaan and the Reusable Launch Vehicle – Technology Demonstrator (RLV-TD) are under development.

• PSLV is configured with four variants like 6,4,2 solid rocket strap-on motors & core alone versions. Variants will be chosen based on the payload weights & orbit to be accomplished. PSLV has been a versatile launch vehicle deployed for launching all the three types of payloads viz. Earth Observation, Geo-Stationary and Navigation. It has got highest success rate and considered as work horse of ISRO.

• GSLV with indigenous Cryogenic Upper Stage has enabled the launching up to 2 tonne class of communication satellites.

• The LVM3 is the next generation launch vehicle capable of launching 4 tonne class of communication satellites and 10 tonne class of payloads to LEOs. The vehicle was developed with completely indigenized technologies including the C25 cryo stage. The launch vehicle has a track record of all successful launches even from the first development flight. The Human rated LVM3 is identified as the launch vehicle for Gaganyaan mission, which is named as HRLV.

• The Small Satellite Launch Vehicle (SSLV) is being developed with complete indigenous technologies to meet the small satellite launch market on demand driven basis.

First Generation: Satellite Launch Vehicle

Satellite Launch Vehicle-3 (SLV-3) was India’s first experimentalsatellite    launch    vehicle,        weighing

17 tonnes and standing 22 metres tall,capable of launching 40 kg payloads into Low Earth Orbit (LEO). On July 18, 1980, SLV-3 was successfully launched from Sriharikota Range (SHAR), and the Rohini satellite, RS-1, was sent into orbit, making India the sixth member of an elite club of space-faring nations.

SLV-3usedopenloopguidance(withastoredpitchprogramme) to steer the vehicle in flight along a predetermined path. The first experimental flight of the SLV-3, in August 1979, was only partly successful. Apart from the July 1980 launch, two more Rohini satellites carrying remote sensing sensors were launched in May 1981 and April 1983, respectively. The successful completion of the SLV-3 project paved the door for further sophisticated launch vehicle projects, including the Augmented Satellite Launch Vehicle (ASLV), Polar Satellite Launch Vehicle (PSLV), and Geosynchronous Satellite Launch Vehicle.

Second Generation: Augmented Satellite Launch Vehicle (ASLV)

With a lift-off weight of 40 tonnes, the 24 m tall ASLV was designed as a five-stage, all-solid propellant vehicle with the purpose of orbiting 150 kg class satellites in 400 km circular orbits.

The Augmented Satellite Launch Vehicle (ASLV) Programme was created to increase the payload capacity to 150 kg, three times that of SLV-3, for Low Earth Orbits. Building on the experience gained from the SLV-3 missions, ASLV proved to be a low-cost intermediate vehicle for demonstrating and validating critical technologies required for future launch vehicles, such as strap-on technology, inertial navigation, bulbous heat shield, vertical integration and closed-loop guidance.

Four developmental flights were done as part of the ASLV programme. The first developmental flight occurred on March 24, 1987 and the second on July 13, 1988. The third developmental mission, ASLV-D3, was successfully launched on May 20, 1992, when SROSS-C (106 kg) was placed into a 255 x 430 km orbit. ASLV-D4, launched on May 4, 1994, orbited SROSS-C2, which weighed 106 kg. It carried two payloads: the Gamma Ray Burst (GRB) Experiment and the Retarding Potentio Analyser (RPA), and it operated for seven years.

Third Generation: Polar Satellite Launch Vehicle (PSLV)

PSLV is India’s third generation launch vehicle. It is the first Indian launch vehicle to be fitted with liquid stages. After its first successful launch in October 1994, PSLV established itself as India’s reliable and adaptable workhorse launch vehicle. The vehicle has launched several Indian and foreign customer satellites. Furthermore, the vehicle successfully

launched two spacecraft, Chandrayaan-1 in 2008 and Mars Orbiter Spacecraft in 2013, which later travelled to the Moon and Mars, respectively. PSLV had Chandrayaan-1 and MOM as feathers in its hat. PSLV-C48 is the 50th launch of PSLV.

PSLV gained the term ‘the workhorse of ISRO’ for continuously delivering various satellites into low earth orbits, particularly the IRS series of satellites. PSLV has been utilized to launch different satellites into geosynchronous and geostationary orbits, such as satellites from the IRNSS Constellation, due to its unequalled reliability.

The PSLV can launch numerous payloads into orbit, hence multi-payload adaptors are employed in the payload fairing. The vehicle’s payload performance and mission adaptability are demonstrated by the complex missions that involve many orbits and satellites. The long series of consecutive successes and multi-satellite launch capability has cemented PSLV’s standing as a dependable, adaptable and economical launcher in the worldwide market.

Facts to remember-

• The launch vehicle has four stages, with two solid and two liquid fuels.

• It is typically used for smaller satellites.

• Types of PSLV

• PSLV-CA: PSLV Core

• PSLV Standard Configuration: PSLV- CA and six strap on motors

• PSLV- XL: with six boosters, high-capacity rocket

• PSLV- QL and PSLV- DL

• Strap-on Motors

• The PSLV-XL, QL, and DL variants rely on 6,4,2 solid rocket strap-on engines to supplement the first stage thrust. However, strap-on rockets are not employed in the core-only version (PSLV-CA).

• Payload it can carry to SSPO (Sun Synchronous Polar Orbit): 1,750 kg

• PSLV is known as ‘the Workhorse of ISRO’ due to its regular delivery of satellites to Low Earth Orbits. It can transport up to 1,750 kg of payload to Sun- Synchronous Polar Orbits at 600 km altitude.

• Payload it can carry to Sub GTO: 1,425 kg

• PSLV has been utilized to launch satellites into geosynchronous and geostationary orbits, including those from the IRNSS constellation, due to its high reliability.

Fourth Generation: Geosynchronous Satellite Launch Vehicle (GSLV)

India developed the Geosynchronous Satellite Launch Vehicle (GSLV) to launch communication satellites into geo transfer orbit using a cryogenic third stage. Initially, Russian-supplied cryogenic stages were employed. The cryogenic stage was later built in-house and introduced

in January 2014, beginning with GSLV D5. This operating fourth-generation launch vehicle consists of three stages and four liquid strap-on rockets. The GSLV Mk II’s third stage is the flight-proven, indigenously produced Cryogenic Upper Stage (CUS). Since January 2014, the car has enjoyed six straight successes.

Facts to remember-

It has three types-

Mk I- this is the GSLV Core

Mk II- This has 4 strap-on motors

Mk III- Solid 200- divides the first solid stage fuel into two pieces to provide additional boost, and is utilized for larger satellites.

• It has a three-stage fuel burn: Solid, Liquid and Cryogenic stages.

• First Stage: GS1

• The first stage of GSLV is derived from the PSLV’s PS1.

• The 138-tonne solid rocket motor is augmented by 4 liquid strap-ons

• Second Stage: GS2

• The second stage of the GSLV uses a single Vikas engine.

• The stage was derived from the PS2 of PSLV, when the Vikas engine demonstrated reliability.

• Third Stage: CUS

• The Liquid Propulsion Systems Centre produced India’s first cryogenic engine, the CE-7.5, as part of the Cryogenic Upper Stage Project (CUSP).

• Payload to GTO: 2,250 kg

• GSLV’s principal payloads are INSAT communication satellites, which operate from geostationary orbits and are deployed in geosynchronous transfer orbits.

• Payload to LEO (Low Earth Orbit): 6,000 kg

Further, GSLV’s capability of placing up to 6 tonnes in Low Earth Orbits broadens the scope of payloads from heavy satellites to multiple smaller satellites.

Fifth Generation: GSLV MK-III

LVM3 has three stages: two solid strap-on motors (S200), one liquid core stage (L110), and a high thrust cryogenic upper stage (C25). The S200 solid motor is one of the world’s largest solid boosters, containing 204 tons of solid propellant. The liquid L110 stage employs a dual liquid engine configuration with 115 tonnes of liquid propellant, and the C25 Cryogenic upper stage employs the wholly indigenous high thrust cryogenic engine (CE20) with a fuel loading of 28 tonnes.

LVM3 is ISRO’s latest heavy lift launch vehicle, designed to send 4000 kg spacecraft to GTO (Geosynchronous Transfer Orbit) in a cost-effective manner. LVM3 is a three-stage launch vehicle made up of two solid propellant S200 strap-

ons and core stages that include the L110 liquid stage, C25 cryogenic stage, equipment bay (EB), and encapsulated assembly (EA). EA consists of the spacecraft, the Payload Adaptor (PLA), and the Payload Fairing (PF). With a lift-off mass of 640 tons, this 43.5 m tall three-stage launch vehicle allows ISRO complete independence in launching bigger communication satellites weighing up to 4000 kg in GTO.

The vehicle takes off with the firing of both S200 boosters. The core stage (L110) is fired at approximately 113 seconds into the flight, during the firing of the S200 stages. Both S200 motors fire for approximately 134 seconds before separating at 137 seconds. During L110 firing, the payload fairing separates at an altitude of 115 km and takes around 217 seconds. At 313s, the L110 burns out and separates, followed by the C25 ignition. The spacecraft is injected into a 180x36000 km GTO (Geosynchronous Transfer Orbit) orbit in 974 seconds.

Facts to remember-

• Core Stage: L110 Liquid Stage

• The L110 liquid stage is powered by two Vikas engines developed at the Liquid Propulsion Systems Center.

• Solid Rocket Boosters: S200

• LVM3 relies on two S200 solid rocket boosters to generate significant thrust during liftoff. The S200 was designed at the Vikram Sarabhai Space Center.

• Cryogenic Upper Stage: C25

• The Liquid Propulsion Systems Centre conceived and constructed the CE-20, India’s largest cryogenic engine, which powers the C25.

• Payload to LEO (Low Earth Orbit): 8,000 kg

• LVM3’s cryogenic stage can launch big payloads into 600 km low Earth orbits.

• Payload to GTO: 4,000 kg

• LVM3 can launch 4 tonne GSAT satellites into geosynchronous transfer orbits.

Miscellaneous: Launch vehicle and Missiles

Small Satellite Launch Vehicle (SSLV)

Small Satellite Launch Vehicle (SSLV) is a 3 stage Launch Vehicle configured with three Solid Propulsion Stages and liquid propulsion-based Velocity Trimming Module (VTM) as a terminal stage. SSLV is 2m in diameter and 34m in length with lift off weight of ~120 tonnes. SSLV is capable of launching ~500kg satellite in 500km planar orbit from SDSC/SHAR. The key features of SSLV are Low cost, with low turn-around time, flexibility in accommodating

multiple satellites, Launch on demand feasibility, minimal launch infrastructure requirements, etc.

Facts to remember-

• Vehicle Configuration

• 2m diameter x 34m long

•
Lift off mass: ~120T

• Three Solid propulsion stages

• Liquid module as terminal stage

• Payload Capability

• Single/Multi Satellites - Nano, Micro and Mini satellites

• Single Satellite up to 500kg in 500km planar orbit

• Three Multiple satellites ranging from 10kg to 300kg into 500km Planar Orbit

• Velocity Trimming Module (VTM)

• Velocity Trimming Module based on 50N Bipropellant Thrusters with 8 nos. of 50N thrusters for RCS and 8 nos. of 50N axial thrusters of Velocity addition.

Reusable Launch Vehicle (RLV)

Reusable Launch Vehicle – Technology Demonstrator (RLV-TD) is one of the most technologically challenging endeavours of ISRO towards developing essential technologies for a fully reusable launch vehicle to enable low-cost access to space. The configuration of RLV-TD is similar to that of an aircraft and combines the complexity of both launch vehicles and aircraft. The winged RLV-TD has been configured to act as a flying test bed to evaluate various technologies, namely, hypersonic flight, autonomous landing and powered cruise flight. In future, this vehicle will be scaled up to become the first stage of India’s reusable two stage orbital launch vehicle.

RLV-TD consists of a fuselage (body), a nose cap, double delta wings and twin vertical tails. It also features symmetrically placed active control surfaces called Elevons and Rudder. This technology demonstrator was boosted to Mach no: 5 by a conventional solid booster (HS9) designed for low burn rate. The selection of materials like special alloys, composites and insulation materials for developing an RLV-TD and the crafting of its parts is very complex and demands highly skilled manpower. Many high technology machinery and test equipment were utilised for building this vehicle.

ISRO’s Own Next-Gen Launch Vehicle (NGLV)

The Indian Space Research Organisation (ISRO) is developing a Next-Generation Launch Vehicle (NGLV) to replace operational systems such as the Polar Satellite Launch Vehicle.

ISRO is considering NGLV, a cost-effective, three-stage to orbit, reusable heavy-lift vehicle with a payload capacity of ten tonnes to Geostationary Transfer Orbit (GTO).

Its strong architecture enables bulk manufacturing, adaptability in systems sub-systems and stages, and quick turnaround times.

Features-

The booster stages will use semi-cryogenic propulsion (refined kerosene as fuel and liquid oxygen (LOX) as an oxidizer).

Potential applications include-

• launching communication satellites,

• distant space missions,

• future human spaceflight, and

• cargo missions.

India’s Anti-Satellite (A-SAT) Missile/Mission Shakti

On March 27, 2019, the Defence Research and Development Organisation (DRDO) successfully neutralised a satellite

in space using an anti-satellite (ASAT) missile as part of Mission Shakti. The successful operation revealed DRDO’s technical capability and ability to defend the country’s assets in space, which is the fourth dimension of combat. The ASAT missile, designated as Prithvi Defence Vehicle Mark-II, takes off to intercept the satellite. It is part of India’s Ballistic Missile Defense Programme. Mission Shakti was a successful ASAT missile test after the interceptor collided with a test satellite in low Earth orbit (LEO) at an altitude of 283 km (176 mi).

The mission was one of the most complex operations undertaken by DRDO, requiring a ground-launched missile to target and deactivate a fast-moving satellite in orbit hundreds of kilometers distant.

Reusable Launch Vehicle- Technology Demonstrator (RLV-TD)

The Reusable Launch Vehicle - Technology Demonstrator (RLV-TD) is one of ISRO’s most technologically complex projects aimed at developing fundamental technologies for a fully reusable launch vehicle that will enable low- cost access to space. RLV-TD is configured similarly to an airplane, combining the complexity of both launch vehicles and planes.

The winged RLV-TD has been designed to serve as a flying test bed for evaluating several technologies, including hypersonic flight, autonomous landing, and powered cruise flight. In the future, this vehicle will be upgraded to become the first stage of India’s reusable two-stage orbital launch vehicle.

The RLV-TD consists of a fuselage (body), a nose cap, double delta wings, and twin vertical tails.

It also has symmetrically arranged active control surfaces known as Elevons and Rudder. This technological demonstration was propelled to Mach 5 by a conventional solid booster (HS9) optimized for low burn rates.

The selection of materials such as specific alloys, composites, and insulation materials for the development of an RLV-TD, as well as the manufacture of its components, is extremely difficult and requires highly specialized labor. This vehicle was built using a large amount of high-tech machinery and test equipment.