BASICS

SPACE TECHNOLOGY

1. What exactly is “space”?

• Kármán line (~100 km) marks the practical edge; above it wings can’t generate lift.

• Environment flips: vacuum (no drag/sound), micro-gravity (continuous free-fall), intense

radiation and micrometeoroids → spacecraft need shielding and hardened electronics.

2. Why do satellites stay up?

• A satellite is always falling toward Earth but moves sideways so quickly that the ground
curves away beneath it, creating a closed path.

• Core vocabulary: altitude (height), inclination (tilt), apogee / perigee (farthest / nearest
points), eccentricity(roundness), Δv (total speed change the mission must supply).

• Exam cue: any option saying “polar geostationary” is wrong—GEO must lie over the equator.

3. Orbit families and their jobs

Orbit family & Current Indian

Height / period Key features Typical uses
shorthand example
160 – 2 000 km · Fast revisit, least energy to Imaging, tech-demo,
Low-Earth (LEO) XPoSat (Jan 2024)
≈ 90 min reach crew labs
Sun-synchronous Crosses Equator at same Uniform-light photos,
~700 km · 98° tilt Cartosat-3
(SSO) local solar time climate series
Medium-Earth 2 000 – 35 786 NavIC Gen-2 NVS-01
Stable mid-range Navigation, data-relay
(MEO) km · 4-12 h (May 2023)
Geostationary Appears fixed over one TV, cyclone watch,
35 786 km · 24 h INSAT-3DS (Feb 2024)
(GEO) longitude broadband
Highly-Elliptical Long dwell over one High-latitude telecom, Russian “Molniya”
Elliptical · 12 h
(Molniya) hemisphere signals intel series

4. How do we get there? – Indian launch-vehicle

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 Recent milestone
Launcher Propellant mix Capability & role
(2023-25)
500 kg to LEO · quick-
SSLV All-solid + velocity-trim module Demo flight Feb 2023
turnaround
Launched XPoSat Jan
PSLV Solid strap-ons + hypergolic core 1.7 t to SSO · workhorse
2024
2.7 t to GTO · medium- Lofted INSAT-3DS Feb
GSLV-F14 Solid, hypergolic, cryogenic
heavy 2024
Delivered
LVM-3 Solid boosters + liquid core + cryogenic 4 t to GTO · heaviest
Chandrayaan-3 2023
Agnibaan Semi-cryogenic kerolox, single-piece 3-D- Sub-orbital tech-demo ·
First flight May 2024
SoRTed printed engine private

5. Anatomy of a satellite — BUS & PAYLOAD

1. Bus (service module)

◦ Power (solar arrays, batteries)

◦ TT&C antennas (telemetry, tracking, command)

◦ Attitude-control (reaction wheels, magnetorquers, micro-thrusters)

◦ Thermal management (heaters, radiators, multilayer insulation)

◦ Propulsion (small thrusters for orbit-keeping / de-orbit)

2. Payload (mission package)

◦ Cameras, SAR radars, telescopes, telecom transponders, science sensors

Mnemonic: Bus = body, Payload = purpose.

6. Six mission classes & examples

Mission class What it delivers 2023-25 highlight

Communication Television, broadband GSAT-24
Meteorology Cloud-motion, cyclone alerts INSAT-3DS
Navigation / PNT Position, navigation, timing NavIC Gen-2 (NVS-01)
Earth-Observation Land-use, disaster mapping NISAR radar mapper (launch window Mar 2025)

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Space Science Cosmic or solar data Aditya-L1 (Sun) · XPoSat (X-ray)
Tech-demo / New hardware, space-situational Agnibaan sub-orbital engine test · DRDO micro-SSA
Defence awareness sats

7. Ground segment (the invisible half)

• Control centres (ISRO ISTRAC, NASA MCC) uplink commands and receive housekeeping
data.

• Downlink stations capture raw payload streams (photos, spectra, weather grids).

• Deep-Space Network uses 18-34 m steerable dishes for Moon, Lagrange-point and
interplanetary spacecraft.

8. Space-mission life-cycle (“C-D-A-L-O-D”)

Concept → Design → Assembly / Integration / Testing → Launch → Operations → Disposal.

Remember: defunct LEO craft should exit orbit within about 25 years.

9. Space debris & India’s SSA leadership

• Debris sources: dead satellites, spent stages, explosion fragments, paint flecks.

• Risk: a 10 cm object at 10 km s⁻¹ equals tank-shell energy; hyper-crowding can trigger

Kessler Syndrome.

• Global mitigation rules: UN Long-Term Sustainability guidelines (2019) + IADC 25-year

disposal.

• Indian actions:

◦ IS4OM monitoring hub (Bengaluru, 2022).

◦ ISSAR 2023 logged ≈ 1.4 lakh conjunction alerts, ~3 000 within 1 km, 23 collision-
avoidance manoeuvres by Indian satellites .

◦ India chaired IADC Apr 2024 and pledged debris-free missions by 2030.

10. Planetary-defence

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 • NEO families: Atira (inside Earth), Aten & Apollo (cross Earth), Amor (graze outside).

• Torino Scale ranks impact risk 0-10 (public info).

• 2024 YR4 scare: Torino 3 in Feb 2025 → refined to Torino 0 after better tracking .

• Toolbox: NASA DART kinetic impact (2022), ESA Hera follow-up launching Oct 2024, global
surveys (Pan-STARRS, ATLAS, new 2-m Indian NEO scope cleared for Ladakh 2024).

11. Space-law & governance

• Outer Space Treaty 1967 – space is the “province of all mankind”, bans WMD in orbit.

• UNCOPUOS – UN committee crafting soft-law guidelines; India active.

• Artemis Accords 2020- – 35 signatories for open, peaceful lunar exploration; India not yet a
party.

• IN-SPACe 2020 – Indian single-window agency facilitating private launches and satellite
services.

12. Current Indian missions & what’s next (April 2025)

Mission Purpose Status

Aditya-L1 Solar corona observatory (L1) Operational (since Sep 2023)
XPoSat Cosmic X-ray polarimetry Operating in LEO
INSAT-3DS Next-gen GEO weather satellite Commissioned Feb 2024
NISAR Dual-band SAR Earth mapper Launch window March 2025
3-crew, 400 km, 3-day human Uncrewed test TV-D2 planned H2
Gaganyaan
spaceflight 2025
Agnibaan orbital 300 kg to LEO (private) First orbital attempt 2026

Glossary – one-line definitions

• Apogee: farthest point of an Earth orbit.

• Perigee: nearest point of an Earth orbit.

• Attitude: orientation of a spacecraft in three axes.

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• Δv (delta-vee): total velocity change a mission must provide.

• Reaction wheel: spinning mass used to twist spacecraft orientation without fuel.

• CubeSat: modular 10 cm cube microsatellite standard (1 U).

• Sun-synchronous Orbit: near-polar LEO crossing equator at same local solar time each pass.

• LEO: orbit band 160–2 000 km above Earth.

• MEO: orbit band between LEO and GEO; usually navigation satellites.

• GEO: equatorial orbit 35 786 km high with 24-hour period.

• GTO (Geostationary Transfer Orbit): elliptical path used to reach GEO.

• Hohmann Transfer: two-burn fuel-efficient orbit change between two circular orbits.

• Bi-elliptic Transfer: three-burn path saving fuel when target orbit radius is very large.

• Molniya Orbit: highly-elliptical, 12-hour orbit providing long dwell over high latitudes.

• Launch Window: time span when trajectory to target orbit is possible.

• TT&C: telemetry, tracking and command radio subsystem.

• SAR (Synthetic-Aperture Radar): active radar that builds high-resolution images regardless
of cloud or light.

• Bus: spacecraft body housing support systems.

• Payload: mission instrument(s) accomplishing objectives.

• CAM (Collision-Avoidance Manoeuvre): orbit tweak to dodge potential impact.

• IS4OM: ISRO System for Safe & Sustainable Operations Management (SSA hub).

• ISSAR: Indian Space Situational Assessment Report (annual debris & conjunction data).

• Kessler Syndrome: cascade of collisions that exponentially increases debris.

• Graveyard Orbit: disposal zone ~300 km above GEO for retired satellites.

• NavIC: India’s regional navigation constellation.

• LVM-3: India’s heaviest operational rocket (formerly GSLV Mk III).

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 • Semi-cryogenic Stage: rocket stage using kerosene + liquid oxygen, higher thrust than
hypergolic.

• Deep-Space Network: network of large ground antennas communicating with distant

spacecraft.

• Torino Scale: public risk index (0-10) for asteroid impacts.

• Kinetic Impactor: spacecraft intended to deflect an asteroid by momentum transfer (e.g.,

DART).

1. Edge of space → vacuum, radiation, micro-gravity.

2. Orbit ladder → LEO → SSO → MEO → GEO → Molniya.

3. Rocket chain → SSLV → PSLV → GSLV-F14 → LVM-3 → Agnibaan.

4. Satellite formula → Bus + Payload; six mission classes.

5. Debris challenge → ISSAR 2023 stats + IS4OM surveillance.

6. Asteroid defence → YR4 scare, DART–Hera kinetic-impactor path.

7. Active Indian flagships → Aditya-L1, XPoSat, INSAT-3DS, NISAR, forthcoming Gaganyaan.

PART 1: ORBITS AND ROCKETS

1. Basics of Satellite Orbit

1.1 What is a Satellite?

• A satellite is an object that moves around a planet or star in a fixed path called an orbit.

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 • Satellites can be:

◦ Natural (e.g., Moon around Earth)

◦ Artificial (man-made satellites like INSAT, GPS satellites)

1.2 What is an Orbit?

• An orbit is a curved path taken by a satellite around a planet due to the balance between:

◦ Gravity pulling it inward

◦ Inertia (tendency of the object to move straight) pulling it outward

• Result: The satellite keeps "falling" toward the planet but never hits it, instead it keeps
revolving.

! Simple Analogy:
Imagine throwing a ball sideways very fast — gravity pulls it down but its forward speed keeps it
falling around Earth, not into it — this is orbit.

1.3 Why Bodies Stay in Orbit? (Simple)

• Earth’s Gravity pulls the satellite inward.

• Satellite's Velocity tries to pull it outward (straight line motion).

• These two forces balance, resulting in continuous revolution around Earth.

Important:

• If gravity > speed ➔ satellite falls back to Earth.

• If speed > gravity pull ➔ satellite escapes into space.

1.4 Important Terms:

Term Meaning
Apoapsis (Apogee for
The farthest point of satellite from Earth in its orbit.
Earth)

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 Periapsis (Perigee for
The closest point of satellite to Earth.
Earth)
Orbital Period Time taken for one complete orbit around Earth.
Orbital Velocity Minimum velocity needed to stay in orbit without falling back.
Minimum velocity needed to break free from Earth's gravity. (~11.2 km/s from
Escape Velocity
Earth)

1.5 How Orbits are Created s

(Simple Steps):

1. Rocket launches satellite at a very high speed.

2. As the rocket reaches desired altitude, it releases the satellite.

3. Satellite moves sideways at a high speed → Earth’s gravity keeps pulling it down.

4. Instead of falling straight down, satellite keeps missing Earth → orbital motion is achieved.

-
Evolution Connection:

First Artificial Satellite: Sputnik-1 (1957) by USSR

First Indian Satellite: Aryabhata (1975)

Today ➔ India has over 50 active satellites in various orbits (communication, navigation, defense,
earth observation).

Orbit = Balance of Gravity + Forward Speed

If either gets disturbed → satellite either crashes or escapes.

2. Types of Orbits

2.1 What are Orbital Types?

• Orbits are classified based on:

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 ◦ Altitude above Earth's surface

◦ Shape (circular/elliptical)

◦ Inclination (tilt relative to Earth's equator)

◦ Purpose (communication, imaging, weather)

Different orbits serve different satellite missions.

! Main Types of Orbits:

I. Circular Orbits

Definition:

• Orbit is perfectly circular (eccentricity = 0).

• Constant distance from Earth at all times.

Examples:

• Low Earth Orbit (LEO)

• Medium Earth Orbit (MEO)

• Geostationary Orbit (special case of circular orbit at GEO altitude)

A) Low Earth Orbit (LEO)

✔ Altitude: 160 km – 2000 km

✔ Orbital Time: 90 min to 2 hours (very fast)
✔ Features:

• Very close to Earth → high-resolution images.

• Less time delay (latency) → good for communication.

• Experiences atmospheric drag → needs regular boosts.

✔ Used for:

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 • Remote sensing (e.g., IRS satellites of India)

• Earth observation

• International Space Station (ISS)

• Spy satellites

✔ Examples:

• ISRO’s Cartosat series

• SpaceX Starlink satellites (for internet)

B) Medium Earth Orbit (MEO)

✔ Altitude: 2,000 km – 35,786 km

✔ Orbital Time: 2 to 12 hours

✔ Features:

• Higher than LEO → covers larger area.

• Lesser drag → more stable.

✔ Used for:

• Navigation satellites (e.g., GPS, Galileo, GLONASS)

• Some communication satellites.

✔ Examples:

• India's NavIC constellation (Indian Regional Navigation Satellite System — IRNSS)

C) Geostationary Orbit (GEO)

✔ Altitude: ~35,786 km above Earth's equator

✔ Orbital Time: 24 hours (matches Earth's rotation)

✔ Features:

• Appears stationary from Earth’s surface.

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 • Fixed location over one point of Earth → excellent for continuous coverage.

✔ Used for:

• TV broadcasting

• Weather monitoring

• Long-range communication

✔ Examples:

• INSAT series (communication satellites of India)

• GSAT series

II. Highly Elliptical Satellite Orbits

" Definition:
·

• Orbit is elongated (elliptical) — eccentricity > 0.

✔ Features:

• Satellite spends more time at higher altitudes (apogee).

• Useful for covering high latitudes (like polar regions).

✔ Used for:

• Communications in northern countries (like Russia).

• Surveillance.

✔ Example:

• Molniya orbit (used by Russia).

III. Transfer Orbits

" Definition:
·

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 • Special type of elliptical orbit used to move satellites from one orbit to another (especially
to reach GEO).

✔ Most famous type:

• Geostationary Transfer Orbit (GTO)

✔ Features:

• Satellite is first launched into an elliptical orbit (perigee low, apogee near GEO).

• Then a final burn circularizes it into GEO.

✔ Used for:

• Launching communication satellites into geostationary orbit.

✔ Example:

• PSLV launches satellites first into GTO → then satellite uses its own engine to reach GEO.

Orbit Time to
Altitude Uses Examples
Type Orbit
Earth observation, remote
LEO 160-2000 km 90 min-2 hrs Cartosat, ISS
sensing
2000-35786
MEO 2-12 hrs Navigation NavIC, GPS
km
GEO ~35786 km 24 hrs TV, Weather INSAT, GSAT
HEO Variable Varies Arctic communication Molniya orbit
Used by PSLV,
GTO Transfer orbit - Moving satellites to GEO
GSLV

LEO = Low, Fast, Close → Imaging

MEO = Middle, Stable → Navigation
GEO = Stationary, 24 hr orbit → TV, Communication
HEO = Elliptical → Polar region coverage
GTO = Parking orbit → Go to GEO!

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 • Polar Orbits (special case of LEO)

◦ Satellite crosses over Earth’s poles during each orbit.

◦ Used for Earth mapping and spying.

• Sun-Synchronous Orbits (SSO)

◦ Special polar orbits → satellite passes the same part of Earth at same local solar time
every day.

◦ Useful for consistent lighting → remote sensing.

Evolutionary Growth:

Era Achievement
1950s First artificial satellite (Sputnik-1) in LEO
Communication satellites into GEO (e.g.,
1960s
Syncom-3)
1970s-80s Earth observation in LEO (Landsat program)
Now Mega-constellations in LEO (e.g., Starlink,
(2020s) OneWeb)

3. Circular Orbits

·
(LEO, MEO, GEO - Deep Dive)

3.1 What is a Circular Orbit?

• Definition:
Orbit where distance from the Earth remains constant throughout.
(Eccentricity = 0 → Perfect circle.)

• Key Properties:

◦ Constant speed around Earth.

◦ Uniform gravitational pull.

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 ◦ Easier calculations of time, fuel, and coverage.

Types of Circular Orbits

A) Low Earth Orbit (LEO)

✔ Altitude: 160 – 2,000 km above Earth.

✔ Orbital Period: 90 minutes to ~2 hours.

✔ Key Features:

• Fast revolution (many orbits per day).

• High-resolution imaging because it's close to surface.

• Low latency communication → better for internet constellations.

• Shorter satellite life (due to atmospheric drag).

✔ Typical Applications:

• Earth observation

• Meteorology

• Reconnaissance (military satellites)

• ISS (International Space Station) operates here.

✔ Indian Examples:

• RISAT series (Radar Imaging Satellites)

• Cartosat series (Remote sensing)

✔ Foreign Examples:

• NASA’s Earth Observing System

• SpaceX’s Starlink internet satellites

B) Medium Earth Orbit (MEO)

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✔ Altitude: 2,000 – 35,786 km.
✔ Orbital Period: ~2 – 12 hours.

✔ Key Features:

• Moderate coverage: larger area than LEO, smaller than GEO.

• Longer satellite life than LEO (less atmospheric drag).

• Moderate latency for communication.

✔ Typical Applications:

• Navigation systems

• Some communication satellites.

✔ Indian Example:

• NavIC (Navigation with Indian Constellation) operates in MEO.

✔ Global Examples:

• GPS (USA)

• Galileo (Europe)

• GLONASS (Russia)

C) Geostationary Orbit (GEO)

✔ Altitude: ~35,786 km exactly over the equator.

✔ Orbital Period: 24 hours — matches Earth's rotation.

✔ Key Features:

• Satellite appears fixed from Earth → "stationary" in sky.

• Constant coverage over a particular area.

• Ideal for communication and weather monitoring.

✔ Drawbacks:

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 • Very high latency (signal delay ~240 ms).

• Expensive to launch satellites so high.

✔ Typical Applications:

• TV Broadcasting

• Weather Forecasting

• Long-range Communication

• Defense Communication

✔ Indian Examples:

• INSAT series (Indian National Satellite System)

• GSAT series (Geostationary Satellite)

✔ Foreign Examples:

• GOES (USA’s weather satellites)

• Astra (Europe’s TV satellites)

Feature LEO MEO GEO

2,000–35,786
Altitude 160–2,000 km 35,786 km
km
Speed Fast Moderate Matches Earth's rotation
Coverage
Small Moderate Very large
Area
Examples Cartosat, ISS NavIC, GPS INSAT, GSAT
Earth observation, TV, weather
Uses Navigation
spying communication

4. Highly Elliptical Satellite Orbits (HEO)

4.1 What is a Highly Elliptical Orbit?

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 • Definition:
Orbit that is stretched (elliptical) rather than circular.

• Key Properties:

◦ Perigee (closest point): Near Earth

◦ Apogee (farthest point): Very far from Earth

◦ Satellite spends more time at Apogee → useful for prolonged observation.

4.2 Purpose:

• Cover high-latitude regions (like Russia, Arctic) that are hard to cover with GEO satellites.

• Useful for communications, weather monitoring, surveillance.

4.3 Examples:

Name Purpose Operator

Molniya Orbit Communications over Russia Russia
Similar to Molniya but
Tundra Orbit Russia
geosynchronous

5. Transfer Orbits

5.1 What is a Transfer Orbit?

• Definition:
An elliptical orbit used to move a satellite from one orbit to another.

• Why needed?

◦ Rockets can't launch satellites directly to GEO (too much fuel needed).

◦ Hence first put into GTO, then satellite moves itself to GEO.

5.2 Types of Transfer Orbits:

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A) Geostationary Transfer Orbit (GTO)

✔ Process:

1. Satellite launched into GTO.

2. Uses its own engines to adjust and circularize into GEO.

✔ Used for:

• Launching Communication Satellites.

✔ Example:

• GSLV Mk-III launches communication satellites into GTO.

B) Hohmann Transfer Orbit (important for missions to planets)

✔ Definition:

• Most fuel-efficient way to move between two circular orbits.

✔ Used for:

• Interplanetary missions (e.g., Mars Orbiter Mission used Hohmann Transfer).

GTO = Parking lot for satellites on their way to GEO

Hohmann Transfer = Best fuel-saving orbital change (Earth to Mars, etc.)

6. Spaceports of India

6.1 What is a Spaceport?

• A spaceport is a launch site from where spacecraft (satellites, rockets) are sent into space.

• It includes:

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 ◦ Launch Pads

◦ Control Centers

◦ Vehicle Assembly Buildings

◦ Tracking and Telemetry Stations

India's Major Spaceports:

A) Satish Dhawan Space Centre (SDSC), SHAR (Sriharikota Range)

✔ Location:

• Sriharikota Island, Andhra Pradesh (East coast)

✔ Why Sriharikota?

• Close to the equator → easier and more efficient launches (Earth's rotation gives extra
speed).

• Open to Bay of Bengal → safe for rocket stages to fall without harming people.

✔ Key Features:

• ISRO’s primary spaceport.

• Has 2 operational launch pads.

• Major launches like PSLV, GSLV, GSLV Mk-III are done from here.

✔ Important Launch Pads:

1. First Launch Pad (FLP) — older one.

2. Second Launch Pad (SLP) — newer, can support larger rockets.

✔ Major Launches:

• Chandrayaan-1, 2, 3

• Mangalyaan (Mars Orbiter Mission)

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 • Aditya-L1

• All major PSLV, GSLV launches.

B) Kulasekharapatnam Spaceport (Upcoming)

✔ Location:

• Kulasekharapatnam, Tamil Nadu (South-east coast)

✔ Why another Spaceport?

• To decongest Sriharikota.

• To support new generation small satellite launch vehicles (SSLV).

• Better suited for polar orbit launches (because rockets can fly southward directly over
Indian Ocean).

✔ Status:

• Under construction (Expected operational ~2025-26).

• Will mostly handle Small Satellite Launch Vehicle (SSLV) missions.

C) Thumba Equatorial Rocket Launching Station (TERLS)

✔ Location:

• Thumba, Kerala (near Thiruvananthapuram)

✔ Speciality:

• Located very close to Earth's magnetic equator — ideal for studying equatorial
atmospheric phenomena.

✔ History:

• First rocket (Nike-Apache) launched by India in 1963.

• Dr. A.P.J Abdul Kalam started his journey here.

✔ Today:
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 • Used mainly for launching sounding rockets (small research rockets for atmospheric
studies).

Spaceport Location Speciality Usage

Sriharikota, Andhra Near Equator, 2 launch
SDSC SHAR All major satellite launches
Pradesh pads
Kulasekharapatnam Polar orbit launches,
Tamil Nadu Under construction
(Upcoming) SSLV
Sounding rockets, atmospheric
TERLS Thumba, Kerala Near magnetic equator
studies

Why Spaceport Location Matters:

• Closer to equator = more speed boost from Earth’s rotation → saves fuel.

• Launch direction over ocean = safer for discarded rocket parts.

• Different orbits (Polar vs Equatorial) require different launch angles.

7. Timeline of Space Program in India — Through the Years

7.1 Starting Point:

• India’s space journey began with a vision:

✔ Peaceful uses of outer space
✔ Socio-economic development (weather forecasting, communication, education)

! Step-by-Step Evolution:

# 1960s: Beginning

• 1962:

◦ Establishment of Indian National Committee for Space Research (INCOSPAR).

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 ◦ Chaired by Dr. Vikram Sarabhai.

• 1963:

◦ First rocket launch (Nike-Apache) from TERLS, Thumba.

◦ Launch site chosen because it's near the magnetic equator.

• 1969:

◦ Formation of ISRO (Indian Space Research Organisation).

◦ Brought space activities under a single umbrella.

# 1970s: Setting Foundations

• 1975:

◦ Aryabhata — India’s first satellite launched (with USSR’s help).

• 1979:

◦ Launch of Bhaskara-I — Earth observation satellite.

• 1979:

◦ SLV-3 First Flight — failed (learning phase).

• 1980:

◦ Rohini Satellite successfully launched by India's own rocket (SLV-3).

# 1980s: Building Capabilities

• 1981:

◦ APPLE — Experimental communication satellite.

◦ Handled first direct television broadcasting experiments.

• 1983:

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 ◦ Operationalisation of INSAT system (Indian National Satellite) for communication and
weather.

• 1987:

◦ First ASLV (Augmented Satellite Launch Vehicle) test flight.

# 1990s: Entering Maturity

• 1992:

◦ ISRO builds IRS (Indian Remote Sensing Satellites) for earth observation.

• 1993:

◦ First successful launch of PSLV (Polar Satellite Launch Vehicle) — Workhorse

launcher.

• 1994-99:

◦ Series of PSLV launches successfully placing remote sensing satellites.

• 1997:

◦ Start of GSLV (Geosynchronous Satellite Launch Vehicle) program for heavier

satellites.

# 2000s: Expanding Horizons

• 2001:

◦ Successful GSLV-D1 launch (using Russian cryogenic stage).

• 2003:

◦ INSAT-3A, INSAT-3E for telecommunication and meteorology.

• 2008:

◦ Chandrayaan-1 launched — India’s first moon mission.

◦ Discovery of water molecules on the Moon surface — global fame!

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# 2010s: Global Recognition

• 2013:

◦ Mangalyaan (Mars Orbiter Mission) launched —

▪ India becomes the first Asian country to reach Mars orbit.

▪ Achieved in first attempt at extremely low cost.

• 2017:

◦ PSLV-C37:

▪ Created world record: 104 satellites launched in one mission!

• 2019:

◦ Chandrayaan-2:

▪ Orbiter successful, lander (Vikram) lost during final descent.

# 2020s: Modern Expansion

• 2020:

◦ IN-SPACe created — boosting private sector participation in space activities.

• 2022:

◦ Launch of SSLV-D1 (Small Satellite Launch Vehicle) — initially partial success.

• 2023:

◦ SSLV-D2 successful — makes SSLV operational.

◦ PSLV-C57 launched Aditya-L1 — India's first mission to study the Sun.

• 2023:

◦ Chandrayaan-3 successful landing on Moon's South Pole region — historic!

• 2024:
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 ◦ Successful ignition test for Semi-Cryogenic engine (PITA) – boosts India's heavy lift
capabilities.

• 2025: (Planned/Expected)

◦ Gaganyaan Mission — India's first crewed space mission (likely late 2025).

Year Major Event

1962 INCOSPAR formed
1969 ISRO formed
1975 Aryabhata satellite
1980 First satellite launch by Indian rocket (SLV-3)
1993 PSLV success
2008 Chandrayaan-1 (Moon mission)
2013 Mangalyaan (Mars mission)
2019 Chandrayaan-2
2023 Chandrayaan-3 and Aditya-L1
2025 Gaganyaan Mission (Expected)

• Aryabhata (1975) = First satellite.

• SLV-3 (1980) = First successful Indian launch.

• PSLV (1990s) = Remote sensing leader.

• GSLV (2000s) = Heavy satellite launcher.

• Chandrayaan-1 (2008) = Water on Moon.

• Mangalyaan (2013) = Mars at first attempt.

• Chandrayaan-3 (2023) = Moon South Pole Landing.

8. ISRO Launch Vehicles —

What is a Launch Vehicle?

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 • A launch vehicle is a rocket system that:

◦ Carries satellites or spacecraft

◦ Lifts them into desired Earth orbit (LEO, MEO, GEO)

◦ Or even sends spacecraft to other planets (like Mars).

! Major Types of ISRO Launch Vehicles

A) Sounding Rockets

✔ Definition:

• Small rockets for scientific experiments at sub-orbital altitudes.

✔ Purpose:

• Study atmospheric phenomena (winds, radiation, ionosphere).

✔ Features:

• Low cost, quick launches.

• Return to Earth after short flight.

✔ Famous Series:

• Rohini Sounding Rockets (RSR) series.

✔ History:

• First rocket launched in 1963 (Nike-Apache from TERLS).

B) Satellite Launch Vehicles (Operational Rockets)

1. SLV (Satellite Launch Vehicle)

✔ Status: RETIRED

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✔ Features:

• 4-stage solid fuel rocket.

• Purpose: To launch small satellites into LEO (~400 kg payload).

✔ Important Launch:

• Rohini Satellite in 1980 (First Indian satellite put into orbit by an Indian-made rocket).

2. ASLV (Augmented Satellite Launch Vehicle)

✔ Status: RETIRED

✔ Features:

• Improved version of SLV.

• 5 stages (all solid).

• Designed for low earth orbits (~150 kg payload).

✔ Problem:

• Multiple failures → helped ISRO learn a lot about stabilization and multiple strap-on
boosters.

Modern Operational Rockets

3. PSLV (Polar Satellite Launch Vehicle)

✔ Nickname:

• ISRO’s Workhorse.

✔ Status: Active
✔ First Successful Launch: 1994
✔ Fuel:

• First and third stages → solid fuel.

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 • Second and fourth stages → liquid fuel.

✔ Payload Capacity:

• Up to 1,750 kg to Sun-Synchronous Polar Orbit (SSO).

• Up to 3,800 kg to LEO.

✔ Special Feature:

• Can launch multiple satellites in one mission (world record: 104 satellites in PSLV-C37).

✔ Major Missions:

• Cartosat series

• Chandrayaan-1

• Mangalyaan (Mars Orbiter Mission)

• Aditya-L1 (Solar mission)

✔ PSLV Variants:

Variant Special Feature

PSLV-CA Core Alone (no strap-on boosters)
PSLV-XL Extra Large boosters (used in Mangalyaan)

4. GSLV Mk-II (Geosynchronous Satellite Launch Vehicle)

✔ Nickname:

• Naughty Boy (earlier reliability issues)

✔ Status: Active
✔ First Successful Launch: 2004 (after several trials)
✔ Fuel:

• 3 stages: Solid + Liquid + Cryogenic (indigenously developed upper stage).

✔ Payload Capacity:

• Up to 2,500 kg to GTO (Geosynchronous Transfer Orbit).

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✔ Special Feature:

• Cryogenic technology → vital for heavy satellite launches.

✔ Major Missions:

• GSAT series

• INSAT-4CR

5. GSLV Mk-III (also known as LVM-3)

✔ Nickname:

• Bahubali Rocket (most powerful Indian launcher)

✔ Status: Active
✔ First Successful Flight: 2017
✔ Fuel:

• 3 stages: Solid boosters + Liquid core stage + Cryogenic upper stage.

✔ Payload Capacity:

• Up to 4,000 kg to GTO.

• Up to 8,000 kg to LEO.

✔ Special Feature:

• Can carry human missions (planned for Gaganyaan).

• Used to launch Chandrayaan-2, Chandrayaan-3, and communication satellites.

✔ Major Missions:

• Chandrayaan-2

• Chandrayaan-3

• Future Gaganyaan mission.

6. SSLV (Small Satellite Launch Vehicle)

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✔ Status: Operational (since 2023)
✔ First Successful Launch: Feb 2023 (SSLV-D2)

✔ Fuel:

• 3 stages: All solid stages + Liquid stage velocity trimming.

✔ Payload Capacity:

• Up to 500 kg to LEO.

✔ Purpose:

• Quick, low-cost launches for small satellites (new demand in private sector).

✔ Special Feature:

• Minimal infrastructure needed → can be launched from smaller spaceports.

✔ Major Missions:

• EOS-07

• Janus-1 (first American payload launched by SSLV)

·
$ Memory Booster Table:

Rocket Status Purpose Max Payload

Retire
SLV Learning launch basics 40 kg
d
Retire
ASLV Improve payload 150 kg
d
~3,800 kg
PSLV Active Polar/Sun-synchronous launches
(LEO)
GSLV Mk-II Active Medium GTO launches ~2,500 kg
GSLV Mk-III Heavy launches, Human ~4,000 kg
Active
(LVM-3) spaceflight (GTO)
SSLV Active Quick small satellite launches ~500 kg (LEO)

Recent Updates (2023-2025):

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Yea Launch
Update
r Vehicle
2023 SSLV Successfully operational after SSLV-D2 mission
Launched Aditya-L1 to Sun-Earth Lagrange
2023 PSLV
Point
2024 GSLV Mk-III Human rated for Gaganyaan (testing phase)
2025 Gaganyaan Crewed flight expected using GSLV Mk-III

9. Latest Updates on Indian Space Program (2023-2025)

Major Mission Updates

A) Aditya-L1 Mission (2023)

✔ What?

• India’s first solar observatory mission.

• Studying Sun’s corona, solar winds, magnetic fields, and their impact on Earth.

✔ Where?

• Placed at Lagrange Point L1 (~1.5 million km from Earth).

✔ Launch:

• PSLV-C57 rocket from Sriharikota.

✔ Significance:

• Helps in space weather forecasting (important for satellites, communications, and power
grids).

B) Chandrayaan-3 (2023)

✔ What?

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 • Third lunar mission — aimed for Moon landing.

✔ Success:

• Soft landing on Moon’s South Pole (first country to do so).

✔ Lander:

• Named Vikram (same as Chandrayaan-2 lander but improved).

✔ Rover:

• Pragyan rover successfully deployed for experiments.

✔ Launch:

• By GSLV Mk-III (LVM-3).

C) XPoSat (2024)

✔ Full Name:

• X-ray Polarimeter Satellite.

✔ Purpose:

• Study polarization of cosmic X-ray sources like black holes, neutron stars.

✔ Launch:

• PSLV-C58 (planned early 2024).

✔ Importance:

• India's first dedicated astronomy mission after Astrosat.

D) Gaganyaan Mission (Expected 2025)

✔ What?

• India's first crewed space mission (human spaceflight program).

✔ Crew:

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 • 3 astronauts (Vyomanauts) — training with Russia + India.

✔ Rocket:

• Modified GSLV Mk-III (human-rated).

✔ Support Systems:

• Launch Escape System (for emergency safety).

• New life support systems developed.

✔ Progress:

• Several abort tests successful.

• Uncrewed test flight (G1) planned before final manned mission.

! Private Sector Involvement — Recent Growth

A) IN-SPACe (Indian National Space Promotion and Authorization Centre)

✔ Purpose:

• Nodal agency under ISRO to support private companies in space activities.

• Approves, guides and monitors private launches.

✔ Impact:

• Skyroot, Agnikul, Bellatrix getting launch approvals.

B) NSIL (NewSpace India Limited)

✔ Purpose:

• ISRO’s commercial arm (operates satellites, sells launch services).

✔ Significance:

• Monetizes ISRO’s capabilities in global market.

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 Private Startups:

Company Achievement
First Indian private company to launch rocket (Vikram-S) in
Skyroot Aerospace
2022
Agnikul Cosmos Developing Agnibaan, India's first customizable launch vehicle
Bellatrix
Focus on satellite propulsion systems
Aerospace

New Technology Developments (2023-2025)

A) Reusable Launch Vehicle (RLV)

✔ Objective:

• Develop rockets that can return and land back safely like aircraft.

✔ Tests:

• RLV LEX mission (Landing Experiment) successful in 2023.

B) Semi-Cryogenic Engine Program

✔ What?

• New engine technology (liquid oxygen + refined kerosene as fuel).

• Cheaper, safer, and more efficient.

✔ Progress:

• Successful ignition tests conducted in 2024.

• Planned for future heavy-lift launchers.

C) New Spaceport at Kulasekharapatnam

✔ Status:

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 • Construction ongoing.

• Will mainly handle polar launches for SSLV and small missions.

✔ Expected Completion:

• 2025-26.

>
Quick Memory Recap:

Topic Highlight
Aditya-L1 Studying the Sun
Chandrayaan-
South Pole Moon landing
3
XPoSat X-ray Astronomy
Gaganyaan India's first human spaceflight
First private rocket (Vikram-
Skyroot
S)
IN-SPACe Private sector booster
NSIL ISRO’s commercial arm
RLV Reusable rocket landing tested

10. Types of Satellites·

— Full Clarity

What is a Satellite (recap)?

• Satellite = Any object that revolves around a planet or star.

• Satellites are of two types:

◦ Natural Satellites → e.g., Moon

◦ Artificial Satellites → Man-made (e.g., INSAT, GPS)

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Main Types of Artificial Satellites (Based on Purpose)

1) Communication Satellites

✔ Purpose:

• Transmit TV, radio, telephone, internet signals across large distances.

✔ Orbit:

• Mostly in Geostationary Orbit (GEO).

✔ Functions:

• Boost communication signals from one location to another.

• Provide satellite phone services, internet, direct-to-home (DTH) broadcasting.

✔ Examples:

• INSAT series (India)

• GSAT series (India)

2) Earth Observation Satellites (EOS)

✔ Purpose:

• Observe and monitor Earth’s surface for weather forecasting, agriculture, disaster
management, resource mapping.

✔ Orbit:

• Mostly in Low Earth Orbit (LEO) or Sun-Synchronous Polar Orbit (SSO) for better surface
coverage.

✔ Functions:

• Capture images of Earth’s surface.

• Monitor natural disasters (cyclones, floods).

• Track deforestation, urban growth.

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✔ Examples:

• Cartosat series (high-resolution imaging)

• RISAT series (Radar Imaging for all-weather monitoring)

• Oceansat (Ocean studies)

3) Navigation Satellites

✔ Purpose:

• Provide precise positioning, navigation and timing information.

✔ Orbit:

• Mostly in Medium Earth Orbit (MEO).

✔ Functions:

• Used in GPS services, aircraft navigation, military tracking, smartphone mapping apps.

✔ Examples:

• NavIC (India's regional navigation system)

• GPS (USA)

• GLONASS (Russia)

• Galileo (Europe)

4) Weather Satellites (Meteorological)

✔ Purpose:

• Monitor weather patterns, atmospheric changes, cyclones, monsoons.

✔ Orbit:

• Some in GEO (continuous monitoring of an area)

• Some in Polar orbits (global coverage).

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✔ Functions:

• Observe cloud patterns.

• Predict storms and monsoon behavior.

✔ Examples:

• INSAT-3D, INSAT-3DR (India)

• Meteosat (Europe)

5) Scientific Satellites (Space Science)

✔ Purpose:

• Conduct scientific experiments in space (astronomy, astrophysics, cosmic studies).

✔ Orbit:

• Varies (depending on mission) — LEO or even special orbits like Lagrange Points.

✔ Functions:

• Study space phenomena like solar activity, cosmic rays, X-rays.

✔ Examples:

• Aditya-L1 (studying the Sun)

• XPoSat (studying cosmic X-rays)

• Astrosat (India's first space observatory)

6) Reconnaissance Satellites (Spy Satellites)

✔ Purpose:

• Military surveillance, border monitoring, strategic intelligence.

✔ Orbit:

• Mostly in LEO for high-resolution imaging.

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✔ Functions:

• Monitor enemy troop movements.

• Detect missile launches.

✔ Examples:

• RISAT-2B (India)

• Cartosat-2 series (dual-use for civilian + military)

7) Technology Demonstrator Satellites

✔ Purpose:

• Test new technologies in space before full use.

✔ Functions:

• Validate satellite design.

• Test new propulsion, communication technologies.

✔ Examples:

• APPLE (India’s early communication tech demo)

• INS-1C (mini-satellite tech demo)

Satellite Type Purpose Orbit Example

Communication TV, Internet GEO INSAT, GSAT
Earth Earth imaging, disaster
LEO/SSO Cartosat, RISAT
Observation management
Navigation GPS services MEO NavIC
GEO/
Weather Meteorology INSAT-3D
Polar
Astrosat, Aditya-
Scientific Research Variable
L1
Reconnaissance Military surveillance LEO RISAT-2B

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Technology
Testing new tech Variable APPLE
Demo

"CENWART" Trick to remember:

Communication – Earth Observation – Navigation – Weather – Astronomy – Reconnaissance –

Technology Demo.

11. Types of Launch Vehicles (Globally)

What is a Launch Vehicle (recap)?

• Launch Vehicle = Rocket system that delivers a payload (satellite/spacecraft) into space.

• It must provide enough speed and height to overcome Earth's gravity.

Rocket = Delivery Van that delivers satellites to their parking spots (orbits).

Classification of Launch Vehicles

1. Based on Mission Type:

A) Orbital Launch Vehicles

✔ Definition:

• Rockets that put payloads into a stable orbit around Earth (LEO, MEO, GEO etc.).

✔ Examples:

• PSLV (India)

• GSLV (India)

• Falcon 9 (USA - SpaceX)

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 • Ariane 5 (Europe - ESA)

B) Suborbital Launch Vehicles

✔ Definition:

• Rockets that enter space but do not achieve orbital speed.

• Follow a parabolic trajectory — come back to Earth without completing one full orbit.

✔ Uses:

• Testing

• Space tourism

• Atmospheric studies

✔ Examples:

• Sounding rockets (India's Rohini series)

• Blue Origin’s New Shepard (USA — space tourism)

2. Based on Stages:

A) Single-stage Launch Vehicles

✔ Definition:

• Entire rocket reaches space without discarding any parts.

✔ Reality:

• Very difficult — almost all modern rockets are multi-stage.

✔ Concept Example:

• Skylon (proposed UK spaceplane, not yet operational)

B) Multi-stage Launch Vehicles

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✔ Definition:

• Rocket sheds used-up parts (stages) during ascent to improve efficiency.

✔ Common Structure:

• 1st stage: Heavy lift from ground

• 2nd stage: Accelerate further

• 3rd stage: Precision orbital insertion

✔ Examples:

• PSLV (4 stages)

• Falcon 9 (2 stages)

• GSLV (3 stages)

3. Based on Propellant Used:

A) Solid Propellant Rockets

✔ Fuel:

• Solid chemical mixtures.

✔ Features:

• Simple design.

• Instant thrust.

• Cannot be shut off once ignited.

✔ Examples:

• SLV (India - 4 solid stages)

• Solid Boosters of PSLV, GSLV Mk-III.

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B) Liquid Propellant Rockets

✔ Fuel:

• Liquid fuel + oxidizer.

✔ Features:

• Can be controlled (thrust can be adjusted).

• Complex plumbing systems.

✔ Examples:

• PSLV (2nd and 4th stages)

• Space Shuttle Main Engines

C) Cryogenic Rockets

✔ Fuel:

• Liquid Hydrogen (LH2) + Liquid Oxygen (LOX) at super low temperatures.

✔ Features:

• Very high efficiency.

• Technologically challenging.

✔ Examples:

• GSLV Mk-II (India's own cryogenic engine CE-7.5)

• GSLV Mk-III (C25 Cryogenic stage)

• Ariane 5 (Europe)

D) Semi-Cryogenic Rockets (New Tech)

✔ Fuel:

• Liquid Oxygen + Refined Kerosene (RP-1).

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✔ Features:

• High thrust.

• Easier to handle compared to full cryogenic.

✔ Examples:

• India is developing Semi-Cryo Engine (SCE-200).

• Russia’s famous RD-180 engine.

4. Based on Reusability:

A) Expendable Launch Vehicles (ELVs)

✔ Definition:

• Single-use rockets → discarded after launch.

✔ Examples:

• PSLV

• GSLV

B) Reusable Launch Vehicles (RLVs)

✔ Definition:

• Rockets (or parts) recovered and used again for multiple missions.

✔ Examples:

• Falcon 9 (SpaceX)

• India’s RLV-TD (technology under testing — Landing experiment done successfully)

Global Major Launch Vehicles ·

Overview (Simple Table)

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 Launcher Country Special Feature
Polar, Geosynchronous, Small satellite
PSLV, GSLV, SSLV India
launches
Falcon 9, Falcon
USA (SpaceX) Reusable boosters
Heavy
Ariane 5, Ariane 6 Europe (ESA) Heavy commercial launches
Long March Series China Versatile family, Moon, Mars missions
Soyuz Russia Oldest operational, Human missions
H3 Rocket Japan New generation commercial launcher

-
>
! Quick Memory Aid:

"OSPL-R" to remember ·
key types:

Orbital → Full Earth orbit

Suborbital → Up and down
Propellants (Solid, Liquid, Cryogenic)
Launch stages (Single, Multi)
Reusability

12. Differences between Indian Launch Vehicles

>
Quick Introduction:

• India uses different rockets for different payload needs:

◦ Light, medium, heavy payloads

◦ LEO, GEO, interplanetary

• Choosing the right rocket depends on:

Payload weight + Destination orbit + Mission type

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Differences:

1. PSLV (Polar Satellite Launch Vehicle)

✔ Purpose:

• For small to medium payloads into LEO / Sun-synchronous polar orbits (SSO).

✔ Features:

• Highly reliable (over 50 successful launches).

• Can carry multiple satellites in one mission.

• Used for: Earth observation, remote sensing, Moon/Mars missions.

✔ Payload Capacity:

• ~1,750 kg to SSO

• ~3,800 kg to LEO

✔ Fuel:

• 4 stages → Solid, Liquid, Solid, Liquid.

✔ Famous Missions:

• Chandrayaan-1

• Mangalyaan (Mars Orbiter Mission)

• Cartosat series

2. GSLV Mk-II (Geosynchronous Satellite Launch Vehicle)

✔ Purpose:

• For medium payloads to Geosynchronous Transfer Orbit (GTO).

✔ Features:

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 • Uses Cryogenic upper stage (CE-7.5 engine).

• Needed for heavier communication satellites.

✔ Payload Capacity:

• ~2,500 kg to GTO

✔ Fuel:

• 3 stages → Solid, Liquid, Cryogenic.

✔ Challenges:

• Initially had reliability issues (hence called "naughty boy").

✔ Famous Missions:

• GSAT satellites

• Communication and weather satellites.

3. GSLV Mk-III (Now called LVM-3 - Launch Vehicle Mk-3)

✔ Purpose:

• For heavy payloads to GTO, human spaceflight missions.

✔ Features:

• India's most powerful rocket ("Bahubali").

• Can launch heavy communication satellites + future manned missions (Gaganyaan).

✔ Payload Capacity:

• ~4,000 kg to GTO

• ~8,000 kg to LEO

✔ Fuel:

• 3 stages → Solid boosters + Liquid core + Cryogenic upper stage (C25 engine).

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✔ Famous Missions:

• Chandrayaan-2

• Chandrayaan-3

• Planned Gaganyaan (human mission)

4. SSLV (Small Satellite Launch Vehicle)

✔ Purpose:

• For small satellites (<500 kg) into LEO.

✔ Features:

• Low-cost

• Quick turnaround

• Minimal ground infrastructure needed.

• Specially for private sector launches.

✔ Payload Capacity:

• ~500 kg to LEO

✔ Fuel:

• 3 solid stages + 1 small liquid stage (for final orbital adjustment).

✔ Famous Missions:

• EOS-07

• Janus-1 (American satellite)

Feature PSLV GSLV Mk-II GSLV Mk-III (LVM-3) SSLV

Main Heavy GTO/LEO + Human Small LEO
LEO/SSO satellites Medium GTO satellites
Purpose missions satellites
~4,000 kg (GTO), ~8,000 kg
Payload ~3,800 kg (LEO) ~2,500 kg (GTO) ~500 kg (LEO)
(LEO)
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 Solid + Liquid + Solid + Liquid
Fuel Type Solid + Liquid Solid + Liquid + Cryogenic
Cryogenic (small)
No. of
4 3 3 4
Stages
Remote sensing, Mars Communication Quick small
Famous for Moon landing, Gaganyaan
mission satellites launches
Nickname Workhorse Naughty boy (initially) Bahubali Mini launcher

"P-G-G-S"
PSLV = Polar
GSLV Mk-II = Geosynchronous (Medium)
GSLV Mk-III = Heavy / Human
SSLV = Small satellites

1. Orbit Types

Orbit Altitude Uses Example

LEO (Low Earth Orbit) 160–2,000 km Earth observation, spy satellites Cartosat, RISAT, ISS
2,000–35,786
MEO (Medium Earth Orbit) Navigation NavIC, GPS
km
TV broadcasting, weather
GEO (Geostationary Orbit) 35,786 km INSAT, GSAT
monitoring
HEO (Highly Elliptical Orbit) Variable Arctic communications Molniya (Russia)
PSLV, GSLV
GTO (Transfer Orbit) Elliptical Move satellites to GEO
missions

2. Indian Spaceports

Spaceport Location Purpose

Sriharikota, Andhra Major satellite launches (PSLV,
SDSC SHAR
Pradesh GSLV)
TERLS Thumba, Kerala Sounding rockets, atmospheric studies
Kulasekharapatnam (Under construction) Tamil Nadu SSLV, polar launches

3. ISRO Rockets Comparison

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 Rocket Payload Orbit Target Special
Polar, LEO,
PSLV ~3,800 kg (LEO) Workhorse
SSO
GSLV Mk-II ~2,500 kg (GTO) GTO Cryogenic upper stage
~4,000 kg (GTO), ~8,000 kg Heavy, Human
GSLV Mk-III (LVM-3) GTO/LEO
(LEO) missions
SSLV ~500 kg (LEO) LEO Quick small launches

4. Satellite Types

Satellite Type Main Use Example

Communication TV, internet signals INSAT, GSAT
Earth Observation Imaging, resource monitoring Cartosat, RISAT
Navigation GPS, positioning NavIC
Cyclone prediction,
Weather INSAT-3D
monsoons
Astrosat, Aditya-
Scientific Space research
L1
Reconnaissance Military surveillance RISAT-2B
Technology Demo Testing new tech APPLE

5. Major Recent Indian Missions (2023-2025)

Mission Purpose Status

Launched 2023,
Aditya-L1 Study of Sun
operational
Chandrayaan- Moon South Pole
Successful 2023
3 Landing
XPoSat X-ray astronomy Planned 2024 launch
Gaganyaan First crewed spaceflight Expected late 2025

6. Global Launch Vehicles Quick Overview

Launcher Country Special Feature

PSLV, GSLV,
India Versatile launches
SSLV

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 USA
Falcon 9 Reusable
(SpaceX)
Ariane 5 Europe (ESA) Heavy commercial launch
Long March China Large satellite programs
Soyuz Russia Crewed missions

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