India’s space programme, led by the Indian Space Research Organisation (ISRO), has evolved from modest beginnings into one of the most respected space agencies in the world. Over the years, ISRO has designed and executed a range of missions—from satellite navigation, Earth observation, interplanetary exploration, to solar studies—that have not only enhanced India’s technological self-reliance but also contributed to global scientific collaboration. Its cost-effective approaches and mission diversity—from Chandrayaan and Mangalyaan to Aditya-L1 and the upcoming Gaganyaan—have become case studies in innovation.

For UPSC aspirants, ISROs journey is more than current affairs—it directly intersects with the syllabus of General Studies Paper 3 (Science & Technology), provides examples for GS Paper 2 (International Relations, Governance), and can enrich perspectives in the Essay Paper, Ethics, and even Optional subjects like Geography or PSIR. In this article, we will explore detailed insights about ISRO GSAT-18 Communication Satellite Mission —its objectives, timelines, key technologies, and strategic implications.

ISRO GSAT-18 Communication Satellite Mission Overview

GSAT-18 Communication Satellite was designed and executed with the primary aim of supporting advancements in Communication.To carry out its objectives, GSAT-18 Communication Satellite targeted Earth.

• For this mission, GSAT-18 Communication Satellite was placed into orbit using Ariane 5 VA-231.
• The spacecraft was sent into orbit from Kourou, French Guiana.
• ISRO developed GSAT-18 Communication Satellite with the core goal of Communication services.
• As a secondary focus, GSAT-18 Communication Satellite was intended to Television, VSAT, digital satellite news gathering.
• The mission is currently in the stage of Operational.

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Timeline & Milestones of ISRO GSAT-18 Communication Satellite Mission

• The mission timeline of GSAT-18 Communication Satellite began with its launch on October 6, 2016.
• Around 2028 (12 year life) was set as the end-of-life marker for the mission’s primary phase.

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ISRO GSAT-18 Communication Satellite Mission Technical Specifications

As a Communication mission, GSAT-18 Communication Satellite was built around a configuration involving I-3K bus, 3404 kg launch mass.Following its launch on October 6, 2016 via Ariane 5 VA-231, the spacecraft was deployed into Geostationary Orbit (GEO).

• As part of GSAT-18, ISRO included C-band, Extended C-band, Ku-band transponders to facilitate the mission’s primary and secondary objectives.
• The mission made use of C-band, Extended C-band, Ku-band, which are standard for applications in Communication operations.
• Critical systems used in GSAT-18 were based on Communication satellite technology.

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GSAT-18 Communication Satellite Launch Information

• GSAT-18 Communication Satellite was successfully launched on October 6, 2016 by ISRO.
• The launch of GSAT-18 Communication Satellite was carried out by the Ariane 5 VA-231.
• The vehicle was launched from Kourou, French Guiana.

Who are the Stakeholders & Collaborators?

ISRO were involved in various phases of the mission.As per available data, Arianespace were part of the commercial framework of the mission.

Outputs, Applications & Impact of ISRO GSAT-18 Communication Satellite Mission

Mission documentation identifies Augmented INSAT/GSAT system capacity as a milestone in the Communication program.Among its contributions, GSAT-18 Communication Satellite delivered information on Communication and broadcast services.

• Television broadcasting, VSAT services, digital satellite news gathering reflects the broader civilian value of GSAT-18 Communication Satellite.
• ISRO launched GSAT-18 Communication Satellite to address long-term needs such as Augmented communication satellite capacity for national needs.
• Planned missions including Future communication satellites for expanding services are anticipated to carry forward the objectives and advancements initiated during GSAT-18.

ISRO GSAT-18 Communication Satellite Space Mission Risks, Failures & Mitigation

UPSC Relevance of ISRO GSAT-18 Communication Satellite Space Mission

• Understanding the basic structure of ISRO, its launch centres, and satellite series (such as GSAT, INSAT, or CARTOSAT) is crucial for tackling Prelims questions with precision.
• ISRO missions are highly relevant to UPSC Mains, particularly in GS Paper III, where candidates must understand the role of space technology in development, disaster management, communication, and governance.
• The ethical use of space for peaceful purposes, as consistently upheld by ISRO, resonates with values-based questions in GS Paper IV.
• For Physics or Engineering-based optionals, ISRO’s propulsion systems, orbital mechanics, or sensor technologies offer real-world illustrations of core theories.

Past UPSC Mains PYQs on ISRO Space Missions

Q1. Discuss the role of the private sector in the growth of the space industry in India. How has the governments policy of 2023 affected it? (2023, GS Paper 3 - Science & Technology)

Q2. What is India’s plan to have its own space station and how will it benefit our space programme? (2022 & 2019, GS Paper 3 - Science & Technology)

Q3. Space has been the next big frontier for mankind after sea and land. In this context, discuss Indias policy and preparedness for space wars. (2019, GS Paper 3 - Science & Technology)

Q4. Discuss the utility of the Mars Orbiter Mission (MOM) for India. (2016, GS Paper 3 - Science & Technology)

Q5. What do you understand by Standard Positioning Systems and Precision Positioning Systems in the GPS era? Discuss the advantages India perceives from its ambitious IRNSS programme employing just seven satellites. (2015, GS Paper 3 - Science & Technology)

Past UPSC Prelims PYQs on ISRO Space Missions

Q1 [2025]: GPS-Aided Geo Augmented Navigation (GAGAN) uses a system of ground stations to provide necessary augmentation. Which of the following statements is/are correct in respect of GAGAN?

I. It is designed to provide additional accuracy and integrity.
II. It will allow more uniform and high quality air traffic management.
III. It will provide benefits only in aviation but not in other modes of transportation.

Select the correct answer using the code given below.

(a) I, II and III
(b) II and III only
(c) I only
(d) I and II only

Correct Answer: (d) I and II only

Explanation: Statements I and II correctly describe the core purpose and benefit of the GAGAN system. (I) GAGAN is designed to augment GPS signals by correcting for errors, which provides much greater accuracy and guarantees the integrity (reliability) of the positioning information. (II) This enhanced accuracy and reliability directly enables more precise aircraft routing and landing procedures, thus improving the uniformity and quality of air traffic management.

Q2 [2022]: If a major solar storm (solar flare) reaches the Earth, which of the following are the possible effects on the Earth?

1. GPS and navigation systems could fail.
2. Tsunamis could occur at equatorial regions.
3. Power grids could be damaged.
4. Intense auroras could occur over much of the Earth.
5. Forest fires could take place over much of the planet.
6. Orbits of the satellites could be disturbed.
7. Shortwave radio communication of the aircraft flying over polar regions could be interrupted.

Select the correct answer using the code given below:

(a) 1, 2, 4 and 5 only
(b) 2, 3, 5, 6 and 7 only
(c) 1, 3, 4, 6 and 7 only
(d) 1, 2, 3, 4, 5, 6 and 7

Answer: The correct answer is (c).

Explanation: A major solar storm can disrupt GPS, power grids, satellite orbits, polar radio communication, and cause auroras, but cannot trigger tsunamis or forest fires.

Q3 [2020]: The experiment will employ a trio of spacecraft flying in formation in the shape of an equilateral triangle that has sides one million kilometres long, with lasers shining between the craft.” The experiment in question refers to

(a) Voyager-2
(b) New horizons
(c) Lisa Pathfinder
(d) Evolved LISA

Answer: The correct answer is (d) Evolved LISA.

Explanation: Evolved LISA (Laser Interferometer Space Antenna) is a planned space-based gravitational wave observatory by ESA and NASA, using three spacecraft in a triangular formation with laser beams to detect cosmic gravitational waves.

Q4 [2016]: Consider the following statements:

The Mangalyaan launched by ISRO

1. is also called the Mars Orbiter Mission
2. made India the second country to have a spacecraft orbit the Mars after USA
3. made India the only country to be successful in making its spacecraft orbit the Mars in its very first attempt

Which of the statement(s) given above is/are correct?

(a) 1 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3

Answer: c) 1 and 3 only

Explanation: Mangalyaan is the informal name of Mars Orbiter Mission (MOM), launched by ISRO on 5 November 2013 and India is the only nation to date to have succeeded on its maiden attempt.

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UPSC Practice Questions on ISRO Space Missions

Q1. Which report did ISRO release in 2023?
1. Indian Space Situational Assessment Report ISSAR
2. Space Exploration Strategy Report SESR
3. Mars Mission Report MMR
4. Lunar Exploration Report LER
Answer: 1
Solution: Indian Space Situational Assessment Report ISSAR was released by ISRO in 2023. This report provides a comprehensive assessment of space situational awareness, covering aspects such as satellite health, space debris, and potential collision risks. The ISSAR is crucial for ensuring the safety and sustainability of space operations by monitoring and managing space traffic. It reflects ISRO's commitment to addressing the challenges posed by increasing congestion in Earth's orbit.

Q2. What is the thrust class of the SCE-200 liquid rocket engine developed by ISRO?
1. 1MN
2. 2MN
3. 3MN
4. 4MN
Answer: 2
Solution: The thrust class of the SCE-200 liquid rocket engine developed by ISRO is 2MN. The SCE-200 is a semi-cryogenic engine being developed to power future launch vehicles of ISRO. This engine runs on a combination of liquid oxygen LOX and kerosene RP-1, which provides higher efficiency and performance. The development of the SCE-200 is part of ISRO's efforts to enhance its launch capabilities and reduce dependency on foreign technology.

Q3. Which of the following are the major missions of Indian Space Research Organization in 2023?
1. Chandrayaan-3
2. Solar Mission Aditya-L1
3. Liquid fuel powered rockets
4. Solar powered rockets
Select the answer using the code given below:
1. 1 and 2 only
2. 1, 2 and 3
3. 3 and 4 only
4. 1, 2, 3 and 4
Answer: 1
Solution: Major Missions of Indian Space Research Organization in 2023 include Chandrayaan-3 and Solar Mission Aditya-L1. Chandrayaan-3 aims to demonstrate the ability to perform a soft landing on the Moon, while Solar Mission Aditya-L1 is India's first dedicated mission to study the Sun. Liquid fuel powered rockets and solar powered rockets are not considered major missions by themselves.

Q4. Which Hyderabad-based startup received approval from IN-SPACe to offer Ground Stations as a Service GSaaS?
1. Pixxel
2. Dhruva Space
3. Skyroot Aerospace
4. Agnikul Cosmos
Answer: 2
Solution: Hyderabad-based Dhruva Space has received approval from the Indian National Space Promotion and Authorisation Center IN-SPACe to offer Ground Stations as a Service GSaaS. GSaaS offers a cost-effective alternative to traditional ground station setups in India, reducing high upfront costs. IN-SPACe is an independent agency that promotes and facilitates private sector participation in space activities.

Q5. Which of the statements regarding ASAT are true?
I. ASAT is a missile-based system to attack moving satellites.
II. India, using ASAT Missile, destroyed a live satellite in Low Earth Orbit.
III. ASAT missile is capable of shooting down targets moving at a speed of 50 km per second at an altitude as high as 2000 km.
1. I and II only
2. I and III only
3. I, II and III
4. II and III only
Answer: 1
Solution: ASAT Anti-Satellite Weapon is a missile-based system to destroy satellites in orbit, which can degrade the adversary's space capabilities. India successfully tested its ASAT missile under Mission Shakti on March 27, 2019. The test involved shooting down a live satellite in Low Earth Orbit at an altitude of around 300 km.

Q6. Consider the following statements with reference to Gaganyaan:
I. Gaganyaan is an Indian crewed orbital spacecraft intended to be the formative spacecraft of the Indian Human Spaceflight Programme.
II. ISRO announced Vyommitra, a Male Robot who will accompany other astronauts in the mission.
III. The crewed vehicle is planned to be launched on ISRO's GSLV Mk II.
IV. Defence Research and Development Organisation DRDO will provide support for critical human-centric systems and technologies in this mission.
Which of the statements given above are correct?
1. I and II only
2. I and III only
3. II and IV only
4. I and IV only
Answer: 4
Solution: Gaganyaan is an Indian crewed orbital spacecraft intended to be the formative spacecraft of the Indian Human Spaceflight Programme. The Defence Research and Development Organisation DRDO will provide support for critical human-centric systems and technologies in this mission. The Vyommitra robot is a female robot announced by ISRO to accompany astronauts in the mission, not a male robot. The crewed vehicle is planned to be launched on ISRO's GSLV Mk III, not GSLV Mk II.

Q7. Who is the project director of India's Moon Mission, Chandrayaan 3?
1. Vikram Sarabhai
2. S. Somnath
3. Ritu Karidhal Srivastava
4. P. Veeramuthuvel
Answer: 4
Solution: P. Veeramuthuvel is the Project Director of India's Moon Mission, Chandrayaan 3. Chandrayaan 3 is India's third lunar exploration mission under the Indian Space Research Organisation ISRO. The mission aims to demonstrate the capability for a safe and soft landing on the lunar surface.

Q8. Which Launcher is used for Chandrayan-3?
1. GSLV
2. LVSM
3. GSLV-Mk3
4. PSLV
Answer: 3
Solution: The GSLV-Mk3, also known as the LVM-3 Launch Vehicle Mark-3, is the launch vehicle used for Chandrayaan-3. It is an expendable launch vehicle developed by the Indian Space Research Organisation ISRO. The GSLV-Mk3 is capable of carrying heavier payloads and is crucial for launching large satellites and interplanetary missions.

Q9. Who has been appointed as the new Chief of ISRO?
1. S. Somanath
2. Dr. V. Narayanan
3. K. Sivan
4. A.S. Kiran Kumar
Answer: 2
Solution: Dr. V. Narayanan is a renowned scientist who has contributed significantly to ISRO's propulsion systems. He has played an integral role in the development of cryogenic and semi-cryogenic propulsion systems used in India's space missions.

Q10. When was ISRO's first solar mission Aditya L1 mission launched successfully?
1. 2nd August, 2023
2. 2nd September, 2023
3. 15th August, 2023
4. 15th September, 2023
Answer: 2
Solution: ISRO successfully launched its first solar mission, Aditya L1, on 2nd September 2023 from the Satish Dhawan Space Centre in Sriharikota, Andhra Pradesh. The mission aims to study the Sun's corona, solar winds, magnetic fields, and other solar phenomena to improve our understanding of space weather.