Indian Space Research Organisation(ISRO): Notes | UPSC


Indian Space Research Organisation (ISRO) is the primary space agency of India, established in 1969 with its headquarters in Bengaluru, Karnataka. It is a government-owned organization under the Department of Space, which is responsible for India’s space program and the development of related technology.

ISRO is known for its cost-effective space missions and has gained a reputation for its expertise in developing and launching satellites for various applications.

History of the Indian Space Research Organisation (ISRO)

India’s journey towards space exploration began in the 1960s when the Indian National Committee for Space Research (INCOSPAR) was established under the leadership of Dr. Vikram Sarabhai, the father of the Indian space program. In 1969, the INCOSPAR was transformed into the Indian Space Research Organisation (ISRO).

First Satellite: ISRO’s first satellite, Aryabhata, was launched on April 19, 1975, using the Soviet Union’s Kosmos-3M launch vehicle. Aryabhata was a small satellite weighing 360 kg and was launched from the Kapustin Yar range in Russia.

SLV-3: In 1983, ISRO successfully launched the Satellite Launch Vehicle-3 (SLV-3), which was India’s first indigenously built launch vehicle. The SLV-3 was a four-stage rocket that could carry a satellite weighing up to 40 kg into a low-earth orbit.


Polar Satellite Launch Vehicle (PSLV): In 1993, ISRO launched the Polar Satellite Launch Vehicle (PSLV), which became the workhorse of ISRO’s launch vehicles. The PSLV has since then launched many of ISRO’s satellites, including the Chandrayaan-1 and Mangalyaan missions.

GSLV: In 2001, ISRO launched the Geosynchronous Satellite Launch Vehicle (GSLV), which was designed to launch satellites into geosynchronous orbit. The GSLV uses an indigenous cryogenic engine and is capable of launching satellites weighing up to 2,500 kg.

Mars Orbiter Mission: In 2014, ISRO made history by successfully placing the Mars Orbiter Mission (MOM), also known as Mangalyaan, in orbit around Mars. ISRO became the first space agency in the world to achieve this feat in its maiden attempt.

Recent Developments: In recent years, ISRO has made significant progress in developing advanced space technologies, such as the reusable launch vehicle (RLV) and the Gaganyaan program, India’s first human spaceflight program.

ISRO has come a long way since its establishment and has played a critical role in India’s technological and scientific advancement. ISRO’s achievements in space exploration have brought India to the forefront of space technology, and the agency’s future plans demonstrate its ambitious roadmap for space exploration and technological advancements.

Types of Launch Vehicles/ Rockets

  1. Polar Satellite Launch Vehicle (PSLV)
  2. Geosynchronous Satellite Launch Vehicle (GSLV)
  3. Small Satellite Launch Vehicle (SSLV)
  4. Reusable Launch Vehicle-Technology Demonstrator (RLV-TD)
  5. Augmented Satellite Launch Vehicle (ASLV)
  6. Unified Modular Launch Vehicle (UMLV)
ISRO Launch Vehicles Rockets UPSC
ISRO Launch Vehicles/Rockets

Stages of Rocket


A rocket is a vehicle that obtains thrust by expelling mass in one direction, thus propelling itself in the opposite direction. A rocket typically consists of several stages, each containing one or more rocket engines, fuel tanks, and other systems required for the operation of the rocket.

Here are the general stages of a rocket:

  1. First stage
  2. Second stage
  3. Third stage (if present)
  4. Payload section (also known as the fourth stage)
  5. Fairing (if present)

First Stage: The first stage is the bottommost stage of the rocket, which ignites at liftoff and provides the initial thrust required to lift the rocket off the launch pad. The first stage contains the primary rocket engines and the fuel tanks.

Second Stage: The second stage is typically smaller than the first stage and ignites after the first stage has been jettisoned. The second stage provides additional thrust to the rocket and propels it to a higher altitude or velocity.

Third Stage: The third stage is used to further increase the rocket’s altitude or velocity after the second stage has been jettisoned. The third stage is typically smaller than the second stage and is used for missions that require the rocket to reach higher altitudes or velocities.


Payload Section: The payload section is part of the rocket that carries the spacecraft or satellite into orbit. It is typically located on the top of the rocket and is designed to protect the payload during launch and ascent.

Fairing: The fairing is a protective structure that surrounds the payload and separates it from the rest of the rocket. It is typically jettisoned once the rocket reaches a certain altitude to reduce the weight and drag of the rocket.

ISRO’s launch vehicles have different configurations and number of stages depending on the mission requirements. For example, the PSLV has four stages, while the GSLV Mk III has three stages

Types of Orbit

There are various types of orbits that a satellite can be placed in, depending on the mission requirements. Here are some of the commonly used orbit types:

  1. Geostationary Orbit (GEO): A geostationary orbit is a circular orbit that is 35,786 km above the Earth’s equator. Satellites in GEO complete one orbit in the same amount of time that the Earth takes to rotate once on its axis, which is approximately 24 hours. This allows the satellite to appear stationary in the sky, which is useful for communication and broadcasting applications.
  2. Low Earth Orbit (LEO): A low Earth orbit is an orbit that is between 160 km to 2,000 km above the Earth’s surface. Satellites in LEO orbit the Earth in about 90 minutes and are useful for remote sensing and Earth observation applications.
  3. Medium Earth Orbit (MEO): A medium Earth orbit is an orbit that is between 2,000 km to 35,786 km above the Earth’s surface. Satellites in MEO are used for global navigation satellite systems, such as GPS.
  4. Sun-synchronous Orbit (SSO): A sun-synchronous orbit is a type of polar orbit that is synchronized with the Earth’s rotation around the Sun. Satellites in SSO are useful for Earth observation and remote sensing applications.
  5. Highly Elliptical Orbit (HEO): A highly elliptical orbit is an orbit that is highly elongated, with a high point (apogee) far from Earth and a low point (perigee) close to Earth. Satellites in HEO are useful for communication and navigation applications, especially in high latitudes.

ISRO has launched satellites into all of these orbit types, depending on the mission requirements.

ISRO’s Achievements in Space Technology

ISRO (Indian Space Research Organization) has achieved significant milestones in the field of space technology since its establishment in 1969. India’s space program is recognized for its cost-effective approach to space missions and the development of advanced technologies. Here are some of ISRO’s notable achievements in space technology.

1. Launch of Chandrayaan-1

  • Chandrayaan-1 was India’s first lunar mission, launched on 22nd October 2008, from Satish Dhawan Space Centre, Sriharikota.
  • The spacecraft consisted of an orbiter and a Moon Impact Probe (MIP). The mission’s primary objective was to detect water on the moon and map its surface.
  • It carried eleven scientific instruments from India and six from other countries.
  • The mission successfully discovered water molecules on the moon’s surface and provided data on its mineral composition and topography.

2. Launch of Mars Orbiter Mission (MOM)

  • MOM, also known as Mangalyaan, was launched on 5th November 2013, from Sriharikota.
  • It was India’s first interplanetary mission and the first country to successfully launch a Mars mission on its first attempt.
  • The mission’s primary objective was to study Mars’ atmosphere, surface, and mineral composition.
  • MOM orbited Mars on 24th September 2014, and the mission was considered a significant achievement, considering the low cost of the mission.

3. Indian Regional Navigation Satellite System (IRNSS)

  • IRNSS, also known as NavIC (Navigation with Indian Constellation), is India’s indigenous navigation system.
  • It consists of seven satellites, three in geostationary orbit and four in geosynchronous orbit.
  • The system provides accurate positioning and timing information across India and the surrounding region, covering an area of approximately 1,500 km around India.
  • The system is designed to provide reliable positioning services for both civilian and military purposes.

4. Geosynchronous Satellite Launch Vehicle Mark III (GSLV Mk III)

  • GSLV Mk III is India’s heavy-lift launch vehicle capable of carrying payloads of up to 4 tonnes into geosynchronous transfer orbit (GTO).
  • It was first launched on 5th June 2017, from Sriharikota.
  • The launch vehicle is essential for India’s future space missions as it can carry heavier payloads, including communication satellites and scientific instruments.

5. Advanced Earth Observation Satellite – Cartosat-3

  • Cartosat-3 is India’s most advanced Earth observation satellite launched on 27th November 2019.
  • The satellite can capture images with a resolution of up to 25 cm, making it the most advanced Earth observation satellite developed by India to date.
  • The primary objective of the mission was to provide high-resolution imagery for cartographic applications, urban and rural applications, coastal land use, and regulation.

6. Space Capsule Recovery Experiment (SRE)

  • SRE was a significant achievement of ISRO, launched on 10th January 2007, from Sriharikota.
  • It was a precursor to the human spaceflight program and the first Indian spacecraft to return to Earth from orbit.
  • The capsule landed in the Bay of Bengal after spending 12 days in orbit, performing experiments in microgravity conditions.

ISRO’s achievements demonstrate its capability to develop and launch advanced technologies, establishing India as a significant player in the global space industry. These achievements have also inspired future space missions, including the Gaganyaan mission, Aditya-L1, lunar polar exploration mission, and Venus mission.

Observation Satellite of ISRO

ISRO has launched several Earth observation satellites for a variety of purposes, such as remote sensing, climate monitoring, disaster management, and natural resource management. Here is a table summarizing some of ISRO’s Earth observation satellites and their respective applications:

Satellite NameLaunch DateOrbit TypeApplications
Oceansat-1May 26, 1999PolarOceanography, monitoring of sea surface temperature, and detection of potential fishing zones
Cartosat-1May 5, 2005PolarHigh-resolution mapping and surveying
ResourceSat-1October 17, 2003PolarLand and water resource management, forestry, agriculture, and soil mapping
RISAT-1April 26, 2012PolarRadar imaging for agriculture, forestry, and disaster management
INSAT-3DJuly 26, 2013GeosynchronousWeather forecasting and disaster management
Cartosat-2January 10, 2007PolarHigh-resolution mapping, urban and rural planning, and infrastructure development
Megha-TropiquesOctober 12, 2011PolarClimate monitoring, especially the water cycle and energy exchanges in the tropical atmosphere
ResourceSat-2April 20, 2011PolarNatural resource management, including land use and land cover mapping
RISAT-2BMay 22, 2019PolarRadar imaging for disaster management, forestry, and agriculture
Observation Satellites of ISRO

Communication Satellites of ISRO

Here’s a table of some of ISRO’s communication satellites:

Communication SatelliteLaunch DatePurpose
GSAT-6A29 March 2018Mobile communication and data relay
GSAT-115 December 2018High-speed internet and broadband services
GSAT-2914 November 2018Village Resource Centres, DTH services, and VSAT networks
GSAT-195 June 2017High-speed internet and broadband services
GSAT-186 October 2016Direct-to-home television broadcasting, VSAT networks, and digital satellite news gathering
GSAT-1511 November 2015Direct-to-home television broadcasting and VSAT networks
GSAT-145 January 2014Mobile communication and data relay
GSAT-1029 September 2012Direct-to-home television broadcasting, VSAT networks, and satellite-based navigation services
Communication Satellite of ISRO

Note: This table is not an exhaustive list of ISRO’s communication satellites, but rather a selection of some of the notable ones.


ISRO has made significant contributions to the field of space technology and has become a significant player in the global space industry. Its cost-effective approach to space missions and the development of advanced technologies have earned it a reputation for excellence.

The organization’s future plans are ambitious and aim to establish India as a major player in the space industry. For UPSC aspirants, a thorough understanding of ISRO’s achievements, future plans, and technology is essential to crack the exam.

Thank You!

5/5 - (2 votes)

Vikramjit Singh, founder of Newscoop, an esteemed UPSC educational website, helps aspirants prepare for UPSC CSE with 5 years of experience, offering a deep understanding of crucial concepts.

Leave a Reply