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Special Publication ISRO SP 7 1 94

Satellite Launch Vehicle DevelopmentAn experience in self reliance

elivered byDr Kasturirangan

Chairman Space Commission

t

The Institute of Electrical and Electronics Engineers INC.Hyderabad Section

November 21 1994

Indian Space Research OrganisationBangalore


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1 Introduction

The successful accomplishment of PSLV-D2ARS-P2 mission on October 15,

1994 is a major milestone for self-reliance in Indian satellite launchvehicle development.

It was just thirty years ago, Dr Vikram Sarabhai visualised a scenario

like this and started a humble sounding rocket programme in the idyl-

lic fishing village of Thumba. After a technology appreciation phase

through sounding rocket development, the modest SLV-3 programme was

completed giving a feel on disciplines of rocketry. The intermediateASLV programme provided a low cost vehicle for technology insights.

All these have been built into the operational class PSLV programme.

Plan is afoot to produce PSLV and cater to IRS-1 class of missions.

Parallelly GSLV development programme for INSAT class of satellites has

also been taken up. By the end of the century GSLV will be made opera-

tional. New concepts for technology development useful for beyond 2000also have been under study. A brief narration of the progress achieved

in the last three decades in the launch vehicle programme is given in the

following sections.

2 Some Background to Satellite Launch Vehicles

2 1 Orbits

The orbits of common interest are the following:

a) Low earth orbits of about an altitude of 400 km at an inclination

to the equatorial plane for scientific and certain types of communica-

tion applications;

b) Polar orbits at an altitude of 700-900 m which would enable cover-

age of the entire earth and repeated coverage ofrequired areas use-

ful for remote sensing and meteorology;


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c) Unique geosynchronous orbit a t an altitude of about 36,000 km above

the ear th in the equatorial plane useful for communication, meteo-

rology and V broadcasting. Normally Geo-Synchronous Orbit GSO)

is achieved through an intermediate orbit called Geosynchronous

Transfer Orbit GTO) which will be highly elliptical with a perigee

nearest point from the earth) of about 170 km and an apogee farthest

point from the earth) of about 36,000 km. Normally launch vehicles place

the satellite in GTO and satellite apogee motors transfer them to GSO.

2 2 Complexities of Launch Vehicle Design

The realisation of a launch vehicle involves many branches of science

and engineering and sophisticated infrastructure and innovative man-

agement techniques. Hence today only a few countries possess the tech-

nology for the development of launch vehicles in the world. Unlike other

countries where space efforts were initiated first in the defence field,

Indian space programme was conceived with the peaceful uses as its goal.

The launch vehicle systems should withstand the hostile flight envi-

ronment, should be of light weight, cost effective and should be realisable

within reasonable time constraints. Years of developmental efforts are

put to test in a few minutes of flight requiring performances with prac-

tically no margin for error. In this strategic area know-how transfers

are not possible from elsewhere.

2 3 Simulation and Developmental Flights

The complete launch vehicle system cannot be tested to its service condi-

tions on the ground prior to flight. In fact the first few developmental

flights really become the true tes t beds. However one needs to build

simulation beds as extensively as possible and perform hundreds of simu-

lations on ground models to extremes of deviations. They include digi-

tal simulation, hybrid simulation, hardware-in-loop simulation, windtunnel experimentation, etc.


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3 Development of Sounding Rockets

The Indian launch vehicle development programme began with the

establishment of an equatorial rocket launching station at Thumba for

carrying out scientific experiments in aeronomy and astronomy using

borrowed rockets like Judi Dart Centaure and Nike Apache.

The development of sounding rockets itself began with the design fabri-

cation and launching of a small 75 mm diameter Rohini rocket RH-75.

Today we have a family of sounding rockets ranging from RH-75 to RH-

560 capable of launching upto 200 kg payloads to an altitude of 300-400 km for carrying out scientific experiments. The programme facili-

tated our initiation into areas such as propellants fabrication of

motor cases pyros andinstrumentation.

RH 560 Sounding Rocket takes off

3


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4 Development of SLV-3

SLV-3 vehicle, our first experimental launch vehicle, was conceived in

1969 LV-3 is a 22 metre long, four stage vehicle weighing 17 tonne. Allstages used solid propellant. While first and second stage motor cases

were of special steel, the third and fourth stages used fibre glass cases.

The fourth stage served also as the apogee motor for the geostationary

spacecraft, APPLE SLV-3 employed open loop guidance with stored pitch

programme to steer the vehicle in flight along the pre determined trajec-

tory.

Taking advantage of the earth s rotation from west to east at a velocity

of about 1600 kmlhour and other factors, the Sriharikota island located

at 13 N latitude was chosen as the- launch site. This is the world ssecond best launch site for geosynchronous satellites such as INSAT;the first one being Kourou in South America at a latitude of 5 N


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The first SLV-3 experimental flight took place in July 1979. The mission

was only partially successful due to a jammed valve in the second stage

control system resulting in the leak of oxidiser on the

However, valuable flight data on various stages and

obtained for the first time. The mission was repeated a year late

an unqualified success. Two more successful missions of SLV-3

ad itse

could

were ca

ried out in 1981 and 1983.

SLV-3 programme resulted in significant developments in vehicle and

mission design, materials, hardware fabrication, realisation of solid

propellant technology, control power plants, staging systems, inertial

sensors, electronics, testing, integration and check out. The success of

SLV-3 gave the confidence to take up multiple projects of greater com-

plexities.

5 Development of SLV

Even as SLV-3 programme was being implemented, keeping in mind thelong term goal for realising polar and geosynchronous launch capa-

bility for operational class of satellites, the development of Augmented

Satellite Launch Vehicle (ASLV), was undertaken to act as a low cost

intermediate launch vehicle for demonstrating certain complex tech-

nologies.

ASLV is configured as a five stage solid propellant vehicle, weighingabout 40 tonne and having a length of about 23.8 m. The total flight time

of the mission is about 5 seconds. The strap-on stage consists of two

identical m diameter solid propellant motors similar to SLV-3 first

stage, other stages being the same as in SLV-3. Closed loop guidance is

active from the ignition of the second stage motor to the separation of the

third stage. SLV-3 used an open loop system which followed a n on-board stored preplanned trajectory.


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SLV Lift o

The first development flight ASLV-Dl took place on March 24 1987.

The mission failed just after the separation of the strap-on motors. The

detailed failure analysis of the flight data did not indicate any other

vehicle malfunction or mission deficiency other than the non ignition

of the first stage motor. After required modifications ASLV-D2 was

launched on July 13 1988. However this mission also did not succeed.

Based on the findings of Failure ~ n a l y s i s ommittee and Expert Re-view Panel a number of corrective actions were taken many of them

relating to transition between the s trap on stage and first stage. They

included better charac- terisation of vehicle improved stability augrnen-

tation introduction of on-board detection of flight events and extensive

simulations.

The success ofASLV-D3 on May 20 1992 validated all modifications thatwere introduced into ASLV. The repeatable and reliable performance


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of ASLV design was demonstrated by the perfect launch of ASLV-D4 on

May 4, 1994 successfblly injecting the 113 kg SROSS-C2 satellite into

an orbit of about 437 km perigee and 938 km apogee a t an inclination

of 46 .

The SROSS-C2 satellite carried two payloads, namely, gamma-Ray Burst

(GRB) experiment designed by ISRO, for detecting celestial gamma-ray

bursts in the 20 3000 keV energy range and Retarding Potential

Analyser (RPA) designed by National Physical Laboratory (NPL) to

investigate the characteristics of the equatorial and low latitudes

ionosphere and thermosphere. SROSS-C2 is functioning satisfactorily

and giving valuable scientific data.

With two consecutive successful launches of ASLV all the objectives

of this programme have been achieved.6 evelopment of PSLV

The Polar Satellite Launch Vehicle (PSLV) was initiated parallelly in

1982, to develop capability to launch IRS class of 1,000 kg satellites

into a 900 m altitude polar sunsynchronous orbit. This can also launch

about 2,800 kg class satellites into 400 km low earth inclined orbits com-

pared to 150 kg of ASLV PSLV employs liquid propulsion systems for

the first time. It also ensures guided injection of the satellite. PSLV re-

quired new facilities, technologies and industrial backup of much, arger

proportion. During the course of its development, PSLV also derrivedthe benefits from the lessons learnt from ASLV.

6 1 Description of PS V

The 44 metre tall, four stage PSLV, using solid and liquid propulsion

systems alternately for its stages has a take-off weight of about 283

tonne.


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PS V on the launch pedestal

tage systems

The first stage PSI) s the third largest of its class flown in the world.It uses 2.8 m diameter motor case made of maraging steel which was

developed specifically. State of the art Hydroxyl Tbrminated Poly Buta-

diene HTPB) based solid propellant weighing 29 tonne is cast in 5


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segments. The stage provides a maximum thrust of about 460 tonne.

The first stage has six solid strap-on motors PSOM) of 1 0 m diameter.

Each of the strap-ons, similar to the strap-on motor O ~ ~ S L Vrovides a

maximum thrust of 66 tonne. Thus, the first stage of PSLV alone is

equivalent to 14 times the ASLV core.

The liquid second stage PS2) s of 2.8 m diameter and carries 37.5 tonne

of UDMH Unsymmetrical Dimethyl Hydrazine) and N20, Nitrogen

Tetroxide) propellants stored inAluminium alloy tank with the UDMH

and N20, compartments separated by a thin delicate partition. The stage

uses a turbo-pump fed liquid engine. The stage provides a maximum

thrust of 72 tonne.

The third stage PS3) s of 2 .Om diameter with a Kevlar-Epoxy motor case

having 7 tonne of HTPB solid propellant and provides a maximum thrust

of 35 tonne.

The liquid propulsion fourth stage PS4) has a twin engine configuration

with a total propellant loading of two tonne. I t uses MMH Mono MethylHydrazine) and MON Mixed Oxides of Nitrogen) as propellants stored

in titanium alloy tank. These engines are regeneratively cooled and

pressure fed and each of them provide a thrust of 735 kg.

ontrol systems

Each stage has its own control power plants for three axis control.The first stage uses a Secondary Injection Thrust Vector Control SITVC)

system employing strontium perchlorate which is injected through a set

of 24 valves located around the nozzle divergent. This provides control

of the vehicle in pitch and yaw planes. The first stage also uses two

Reaction Control Thrusters RCT) to provide roll control during the

thrust phase and an Auxiliary Control System ACS) during thePSI-PS2 separation regime. In addition to these, one ground-lit strap-


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PS V 2 i o View

1


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on and one air-lit strap-on are provided with independent SITVC sys-

tems to augment roll control in their respective flight regimes.

The second stage is provided with Engine Gimbal Control EGC) sys-tem to provide pitch and yaw control during flight. The roll control is

provided by the Hot Gas Reaction Control System HRCM) which uses

the hot gases bled from the gas generator of the engine.

The control in pitch and yaw planes during the PS3 thrust phase is

achieved using a Flex Nozzle Control FNC) using two electro-mechani-

cal actuators. The roll control during thrust phase of third stage andcontrol in all axes during the long coast of third stage as well as after

burn out of fourth stage till spacecraft separation are provided by the

fourth stage bipropellant Reaction Control System RCS) employing

MMH and MON.

During the thrus t phase of PS4, the control in all the three axes is

achieved by the two axis Engine Gimbal System actuated by two electro

mechanical actuators for each engine.

eatshield

The vehicle electronics contained in the Equipment Bay EB) and the

satellite mounted over the PS4 stage are protected from the hostile at-

mospheric environment by the Heatshield. The bulbous heatshield of3 2 m diameter and 8.3 m length is made of aluminium alloy isogrid con-

struction and having acoustic blankets to protect the spacecraft from ex-

cessive acoustic loading.

Separation systems

Different kinds of separation devices are employed such as ball and

socket type with spring thrusters for separation of strap-ons from corevehicle; Flexible Linear Shaped Charge FLSC) system for first stage;

merrnan band type for second and fourth stages; ball type for third stage


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and zip cord linear bellow system and merman band type for heat shield.

Retro solid motors mounted on PSI and PS2 impart separation veloci-

ties to the spent stages and Ullage motors in PS2 provide positive ac-

celeration to the stage before ignition.

vionics

The equipment bay housed around the PS4 stage contains the Navi-

gation, Guidance and Control system (NGC) processors, Redundant

St rap down Inertial Navigation System (RESINS), Tracking, Telem-

etry and Telecommand (TTC) packages, power supplies, sequencer

electronics etc. The Inertial Guidance system (IGS) performs the h c -

tions of navigation, guidance, attitude control and flight sequencing.

Navigation function is accomplished by RESINS.

Guidance and Control Processor (GCP) generates guidance, control

and sequencing commands. The guidance system has digital autopilot

software to provide the necessary attitude control error functions andcommands. All the on-board telemetry parameters are transmitted

through three different telemetry carriers to the ground using S-band

transmitters. C-band transponders are provided for tracking the vehicle

during the entire flight regime. Tracking is also provided by the use of

S-band range and range-rate transponders. The telecommand on-board

the vehicle is used to terminate the flight by destroying the individual

stages using destruct pym devices in case vehicle deviates from the

defined flight trajectory. During the atmospheric flight of 160 seconds,

an open loop guidance scheme is used, after which the closed loop guid-

ance system ides the vehicle till spacecraft injection.


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While the first developmental launch of PSLV PSLV-Dl on Septem-

ber 20 1993 was not successful in injecting the IRS-1E satellite intoorbit most of the PSLV systems performed normally

The failure of PSLV- D l was primarily due to a software error in the pitch

control loop of the on-board guidance and control processor which

occurs only when the control command exceeds the specified maximum

limiting value. The above pre-set limit value was exceeded due to the

disturbances experienced during transition between the second andthird stages of the rocket. These disturbances were caused by the

programmed stopping of second stage control 3 7 seconds before the

ignition of the third stage leaving the disturbances during the above

period of the second stage uncorrected and the failure of two small

retro rockets leading to a contact between second and third stages dur-

ing the separation of the second stage.

The successful launch of PSLV-D2 on October 15 1994 injecting the 804

kg IRS-P2 satellite into the desired orbit has validated all the corrections

incorporated and the repeat performance of various systems demonstrat-

ing the soundness of the design of the vehicle. Among the major achieve-

ments of PSLV are:

concurrent development of systems and infrastructure;

industry involvement in a major way;

critical review methodologies for such complex and interactive systems;

mission management;

path breaking advances in solid motors liquid stages materials and

fabrication technology for these inertial navigation and guidance sys-


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tems, SITVC, flex nozzle and gimbal control systems, on-board and

ground software, telemetry, aerospace mechanisms, remote vehicle check

out, automatic launch processing systems, ground infrastructure for fab-

rication, testing, launch complex and tracking network. All the majordevelopments and products and facilities established by PSLV will be

useful directly or with modification to GSLY

7 Development of SLV

The sizing of the geostationary satellite launch vehicle (GSLV) had to

consider the increasing space segment capacity demand in the coming

decades, the experience we have gained in launch vehicle technology

and optimal utilisation of PSLV heritage in order to reduce the cost,

improve the time schedule and increase the reliability of operation. A

large number of vehicle design options were studied to evolve an opti-

mum GSLV vehicle design which can cater to two classes of satellites

viz. 1500 kg and 2500 kg class. The chosen configuration is also consis-

tent with range safety and mission constraints. Modularity in design,growth potential.

GSLV is a three stage vehicle, the core being the 129 tonne solid booster

as in PSLV, the second stage being a liquid propulsion system with a

propellant loading of 37.5 tonne again as in PSLV, and the upper stage

being a restartable cryogenic engine with a propellant loading of 12 tonne

and using liquid oxygen and liquid hydrogen. The core with six ASLV

type strap-ons, symbolically represented as (S125 6S9) L37.5 C12,

is capable of launching 1,500 kg payloads into Geostationary Transfer

Orbit (GTO) which forms the Mark version of GSLY By replacing the

Mark strap-ons with four liquid strap-ons of Vikas engine with a

propellant loading of 40 tonne each, GSLV Mark 2 S125 4L40) L37.5

C12 is capable of launching upto 2.5 tonne into GTO. Without any

strap-ons GSLV has almost the same capability as PSLV, and GSLV


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GSLV Project is progressing satisfactorily. The first launch is scheduled

for 1997-98. Following the re-negotiation of the cryogenic technology

contract with Russia Government has approved the indigenous devel-

opment of Cryogenic Upper Stage.

8 Indigenisation Programme

The indigenisation process s tar ted more than 25 years ago with the

launching of RH-75 rockets using indigenous propellants. Since then

all ISRO Centres have taken initiatives for indigenising critical compo-

nentdmaterials required for their programme. This indigenous effort

which has been crucial to the launch vehicle programme all along has

recently been further strengthened in view of the changing geo political

situation. At present the indigenous content of the launch vehicle projects

is about 70 . Imports are only in the area of electronic components and

special materials.

9 Institution Building and National Efforts

The launch vehicle technology growth in the country has been planned

through the creation and maintenance of various technology Centres of

excellence and synergising the efforts through projects with specific

mission goals interfaced through a matrix organisational structure.

The integral participation of academic and industrial partners and an

open review process has enabled ISRO to effectively tap the resources

available outside ISRO for timely implementation of its programmes.

With the W a r n Sarabhai Space Centre in Thiruvananthapuram acting

as the lead-centre for launch vehicle development major responsi-

bilities for design and development of all launch vehicles are shared by

th e Liquid Propulsion Systems Centre also headquartered in

Thiruvananthapuram and SHAR Centre in Sriharikota. The ISRO


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Inertial Systems Unit, Thiruvananthapurarn is responsible for the devel-

opment of inertial sensors and systems. The ISRO Telemetry, Tracking

and Command Network ISTRAC) is responsible for the telemetry andtracking support to all missions.

Also a host of other institutions and over 150 industries are partners

in the launch vehicle programme. Both public and private sector are

involved in the fabrication of a variety of hardware: light alloy struc-

tures for interstages, motor cases, electronic packages, heatshield, pre-

cision coherent radars, etc. In the area of chemicals and materials, forexample, the maraging steel, propellants and HTPB resin are produced

by the Indian industries.

10 Future plans

10 1 Immediate Future

After PSLV-D3 flight in 1995, three PSLV continuation flights are planneda t the rate of one flight per year. Long term action for more flights also

has been approved. It is proposed to improve PSLV performance to 1,000

kg class progressively. The satellite payloads are planned in a modu-

lar way to fully exploit the indigenous launch capability. In a similar

way the next generation of communication satellites INSAT-3) are

planned for a mass of 2,500 kg to be compatible with GSLV. While the

payload mass for the first developmental flight of GSLV may be limited

to about 1,900 kg, GSLV will be augmented to INSAT-3 class over a

period of time.

In addition to fulfilling internal needs, the possibilities of commercial

exploitation of PSLV and GSLV are also kept in mind. Discussions are

also on as to how to make quantum jumps in payload capabilities by de-

veloping new propulsion modules and using them with in conjunction


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with available ones. Some of the concepts considered are larger solid

strap-ons, liquid clustered core, cryogenic booster.

10.2 Long term Future

Whether it is in the context of scientific exploration or resource surveysthrough orbiting space stations or exploration of new planets for habi-

tats from the point of view of dwindling resources on earth or concepts

such as massive solar power systems, it is conceivable to think of the

need for transportation of large payload masses to space. These dreams

can only come true, if the cost of transportation is reduced from the

present by a factor of 10.

Significant cost reductions can occur only when we are able to combine

the aircraft technology and rocket technology concepts. Reusability and

payload fraction of the order of 10 (as compared to less than 1 for

present launch vehicles) are some of the thrust areas of research in space

faring nations.

New break-throughs are required in propulsion combining the prin-ciples of airbreathers like turbojets, ramjets and scramjets. This has

resulted in the concept of combined cycle engines. Other key technologies

include advanced aerodynamics and computational fluid dynamics, new

materials and efficient thermal management system. Strategies for

such complex development need to be evolved nationally and pur-

sued sharing the resources and infrastructure.

Only with such a national perspective will we be able to harness our col-

lective strength to meet the challenge and apply it effectively evenfor an eventual international collaborative effort. As a part of our st ra t-

egy for the future, ISRO has initiated studies and experiments in this

area. With these and the development of cry0 engine, SRO should be

able to direct its serious attention for the development of future trans-


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portation systems depending on the goals set for space activities

beyond 2 000 AD.

onclusion

Having demonstrated its capability in design development and launch

through ASLV and PSLV missions ISRO has set its target for assured

launch services through PSLV in a very short time from now. GSLV

development and its entry into operational phase before the end of the

century will ensure self reliance for launching INSAT class of satellites.

It will also pave the way for ISRO to compete as an equal partner in the

international level.


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bout Dr Kasturirangan

Dr Krishnaswamy Kasturirangan, born in 1940at Ernakulam,

Kerala, took his Bachelor of Science withHonours and Masterof Science degrees in Physics fromthe BombayUniversity. Heobtained his Doctorate Degree in ExperimentalHighEnergyAstronomyin 1971 fromthe Gujarat University, workingat thePhysical Research Laboratory,Ahmedabad.

Joining I R 0 Satellite Centre (ISAC) in 1971, of whichhebecame the Director in 1990, Dr Kasturirangan has held

several importantpositions inthe satelliteprogrammes of ISROstarting from the very first lndiansatellite, Aryabhata. He wasthe Project Director forIndia's first two experimental earth ob-

servation satellites, Bhaskara-l II Subsequently, as the Project Director ofIRS-IA,he di-rected its design, development and operationalisation.IRS-1A launched in March 1988 andits successor, IRS-1B, launched inAugust 1991, as wellas IRS-P2, launched by India's ownlaunchvehicle PSLV inOctober 1994, today constitute the mainelement ofthe NationalNatu-ral Resources Management System (NNRMS)which has been set up by the Government oflndiato optimallymanage the natural resources of the country. DrKasturirangan,as Director,ISAC,also oversaw the development of the second generation, INSATspacecraft (INSAT-2),the first twoof which, INSAT-2~nd INSAT-2B,were successfully launched in July 1992 andJuly 1993. These satellites are providinga major part of the INSATspace segment for tele-communication,TVbroadcasting, meteorologicalservices and disaster warning.The followonsatellites in IRSseries, IRS-1C 1D,three more satellites in INSAT-2series (INSAT-2C, DlE)as wellas IRS-Pseries of satellites for launch on board PSLV are now being built.

DrKasturirangan ook over as Chairman, Space CommissionlSecretary, Department ofSpace,Government of lndia, and Chairman, lndian Space Research Organisation (ISRO) on March31, 1994. In this position, he has already made a mark withtwo successful launches of thelndianbuiltlaunchvehicles, ASLV-D4inMay1994and the PSLV-D2inOctober 1994, the lattercapable of placing 1,000 kg class remote sensing satellites in polar sun-synchronous orbit.PSLV has also proved a number of systems that go intothe India's GSLV for launching2,500kg class of communicationsatellites into geosynchronous tranfer orbit, thus bringing lndia

closer to achieve self-reliance in launch services.


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Dr Kasturirangan's nterests cover, besides satellite technology, space systems management,astronomy and space science management.

Dr Kasturirangan is a Fellow of the lndian National Science Academy (FNA), lndian Academyof Sciences (FASc), NationalAcademy of Sciences of lndia (FNASc) and lndian NationalAcad-emy of Engineering (FNAE). He is also a Fellow of the Institution of Electronics and Telecom-munication Engineers (IETE) and the Astronomical Society of lndia (ASI), Life Member of thelndian Physics Association (IPA), Fellow of the Astronautical Society of lndia and of theNational Telematics Forum. He is also a Member of the InternationalAstronomical Union andof the lnternational Academy of Astronautics.

Dr Kasturirangan is serving, in various capacities, on a number of national and internationalcommittees. He is the Chairman of the Advisory Committee on Space sciences (ADCOS),Member of lnternational Academy of Astronautics' Sub-committee on Mars Exploration, ndianRepresentative in the E E E Space Panel and Chairman of the COSPAR Panel on SpaceResearch in Developing Countries.

Among the several awards Dr Kasturirangan has won are 'Shri Hari Om Ashram PreritDr Vikram Sarabhai Award' for systems analysis and management (1 981), Award of lntercosmosCouncil of the Soviet Academy of Sciences(1981), 'Shanti Swarup BhatnagarAward' for engi-neering sciences (1 983) and 'Shri Om Prakash Bhasin Foundation Award' for space and aero-space (1988) and the Award of the Institution of Engineers (India), Karnataka, for 1992.

Dr Kasturirangan was conferred Padma Shri , in 1982 and Padma Bhushan in 1992 by theGovernment of India.

Published by P PR Unit, ISRO Hq. Antariksh Bhav an, Bangalore-560094 andprinted at S.N. Process Pvt Ltd, Bangalore-560027.

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