India’s Satellites Explained: INSAT, IRS and Beyond

Every time you watch a cricket match on a dish-fed set-top box, check a cyclone warning on your phone, withdraw cash from an ATM in a remote town or open a map to find your way, there is a good chance that a spacecraft orbiting far above the Earth is quietly involved. Indian satellites form one of the most useful, and least noticed, public infrastructures the country has ever built, serving farmers, fishermen, pilots, soldiers, students and ordinary households every single day.

This explainer walks through that story from the beginning. We look at the first modest spacecraft of the 1970s, the great families of satellites that followed (INSAT, GSAT, IRS, Cartosat, RISAT and others), how they help in practical life, and how the business of space is changing as private companies join the Indian Space Research Organisation (ISRO) in orbit.

The Beginnings: From Aryabhata to the SLV-3 Era

India’s space journey began with a very practical idea. In the 1960s, Dr Vikram Sarabhai argued that a poor but ambitious country should use space technology not for prestige but for development: for communication, weather watching and resource management. That vision shaped every satellite programme that followed.

Aryabhata (1975)

Aryabhata, named after the great fifth-century Indian mathematician and astronomer, was India’s first satellite. It was designed and built in India and launched on 19 April 1975 aboard a Soviet launch vehicle. Its modest scientific goals were X-ray astronomy, studies of the upper atmosphere and solar physics. More importantly, it proved that Indian engineers could build, test and operate a spacecraft.

Bhaskara and the early experiments

The Bhaskara satellites, named after the twelfth-century mathematician Bhaskaracharya, followed in 1979 and 1981. They were experimental Earth-observation satellites carrying television cameras and microwave radiometers, and they gave Indian scientists their first hands-on experience of looking at their own land and oceans from orbit. They too flew on Soviet rockets.

Rohini and SLV-3 (1980)

The real turning point was self-reliance in launching. On 18 July 1980, the Satellite Launch Vehicle SLV-3 lifted off from Sriharikota and placed the Rohini RS-1 satellite into orbit. India thereby joined a small club of nations able to launch satellites with their own rockets. The Rohini series, which continued with further satellites in the early 1980s, was small and experimental, yet it carried the programme from dependence to independence.

APPLE (1981)

The Ariane Passenger Payload Experiment, better known as APPLE, was launched in June 1981 on a European Ariane test flight. It was India’s first experimental geostationary communication satellite, and it tested technologies that later made the INSAT system possible.

Communication Satellites: INSAT and GSAT

If one family of Indian satellites touches the largest number of lives, it is the communication fleet. The Indian National Satellite System, or INSAT, was commissioned in the early 1980s, and it brought together telecommunications, television broadcasting and meteorology on a single platform. The early INSAT-1 spacecraft were built abroad, but from the INSAT-2 series in the 1990s, India built its own.

The newer GSAT series continued that story, with more powerful transponders and, in time, high-throughput satellites that carry broadband. These spacecraft sit in geostationary orbit about 36,000 km above the equator, where they appear fixed over one spot in the sky. Together, INSAT and GSAT make up one of the largest domestic communication satellite systems in the Asia-Pacific region.

What the communication fleet carries

• Television and radio: direct-to-home services and feeds that connect broadcasters to cable networks across the country.
• Telephony and data links: connections for remote regions, islands and border areas where fibre and towers are hard to build.
• Broadband: high-throughput GSAT satellites support internet access in under-served areas.
• Tele-education and telemedicine: classrooms and hospitals linked to experts far away.
• Disaster warning: alerts and emergency links that stay up when ground networks fail.

The roots of this role go back to SITE in 1975-76, when educational programmes reached thousands of villages through a borrowed American satellite. That experiment convinced planners that satellites could carry India’s classrooms and newsrooms into its remotest corners.

Earth Observation: The IRS Fleet and Its Descendants

While INSAT looks outward from a high orbit, the Indian Remote Sensing (IRS) satellites circle the Earth much closer, in polar sun-synchronous orbits a few hundred kilometres up. IRS-1A was launched in 1988, and over the following decades India built what is regarded as one of the largest constellations of civilian remote-sensing satellites in the world.

The main sub-families

• Resourcesat: multi-spectral imaging of crops, forests, water bodies and land use.
• Cartosat: high-resolution panchromatic imaging for cartography, urban and rural planning, road alignment and infrastructure monitoring.
• RISAT: radar imaging satellites that can see through clouds and in darkness, which is invaluable during the monsoon and for surveillance.
• Oceansat: ocean colour and wind observation that helps identify fish-rich zones and track ocean conditions.

Why optical and radar both matter

Optical satellites produce pictures much like photographs, but they depend on daylight and clear skies. Radar satellites send their own microwave pulses and record the echoes, so they work at night and through cloud. During the monsoon, when much of India is covered by cloud for months, radar imagery from RISAT-class satellites fills a crucial gap, for example by mapping floods.

The data from these missions is used by government departments, state remote-sensing centres and researchers. It feeds land-use maps, groundwater studies, forest cover assessment, wasteland mapping, urban growth monitoring and the security forces.

Weather and Cyclone Watch from Orbit

Meteorological satellites are among the most life-saving Indian satellites. Weather instruments flew on INSAT from the start, and dedicated spacecraft such as Kalpana-1 (launched in 2002) and the INSAT-3D family later improved matters further. Their imagers watch cloud movement, sea-surface temperature, humidity and cyclone formation across the Indian Ocean every few minutes, and their sounders profile the atmosphere at different heights.

From data to decisions

• Cyclone tracking: forecasters follow a storm from its birth over the Bay of Bengal or the Arabian Sea until landfall, which allows large evacuations in coastal districts.
• Monsoon monitoring: cloud and rainfall estimates support the seasonal forecasts that farmers and water managers rely on.
• Fog, heat and cold waves: satellite pictures support warnings that protect travellers and vulnerable populations.
• Search and rescue: the INSAT system also carries relay payloads that help pick up distress signals from ships and aircraft.

The coast of Odisha is a telling example. After the devastating super cyclone of 1999, the state invested heavily in early warning and evacuation, and in later storms satellite-guided forecasts helped authorities move very large numbers of people out of harm’s way. Satellites alone do not save lives, but accurate and timely warnings make saving them possible.

Navigation: NavIC and GAGAN

A third family of Indian satellites helps users know where they are. NavIC, the Navigation with Indian Constellation (earlier called the Indian Regional Navigation Satellite System, or IRNSS), is India’s own regional positioning system. It combines satellites in geostationary and inclined geosynchronous orbits and covers India and a surrounding region of about 1,500 km. Its design reflects a lesson learned from past conflicts: a country should not depend entirely on someone else’s navigation signal for strategic needs.

GAGAN (GPS Aided GEO Augmented Navigation) is a different system. It improves the accuracy and reliability of existing satellite navigation signals over Indian airspace, mainly for civil aviation. It is operated with the Airports Authority of India, and its correction signals are broadcast from geostationary satellites. Both systems are described in more detail in our dedicated NavIC story, so we keep it brief here.

• Civil uses: vehicle tracking, fishermen’s safety alerts, power-grid timing and mapping.
• Strategic uses: a restricted service intended for the armed forces and government.

Scientific, Student and Small Satellites

Not every satellite looks down at Earth or relays a signal. Some look at the universe. AstroSat, launched in September 2015, is India’s first dedicated multi-wavelength space observatory. It studies cosmic objects in visible, ultraviolet and X-ray bands, and it has been used to observe black holes, neutron stars and distant galaxies. It was a rare achievement for a developing country at the time.

The rise of small satellites

India has also seen a boom in small satellites. Universities and engineering colleges have built nanosatellites and student satellites, often launched as secondary payloads on ISRO rockets. These low-cost missions train a new generation of engineers and let institutions test experimental sensors cheaply.

The Polar Satellite Launch Vehicle (PSLV) became the workhorse for such rides. In February 2017, a single PSLV mission placed 104 satellites into orbit, which was a world record at the time and made the point that Indian rockets could deliver many small payloads economically.

• Technology demonstrators: small experimental spacecraft that try out new components before large missions use them.
• Student satellites: academic missions that give hands-on experience in design, testing and operations.
• Commercial small satellites: imaging and data constellations from start-ups.

How Satellites Serve Everyday Life

The fleet’s value is easiest to see in ordinary activities. Consider a few areas where Indian satellites quietly do their work.

Agriculture and water

Satellite images help estimate crop area and condition, assess drought, and monitor soil moisture and reservoir levels. Government programmes use remote-sensing data for crop forecasting and insurance assessment, which makes precision agriculture more practical for a country with a very large number of small farms.

Mapping and planning

High-resolution Cartosat images help planners prepare maps for towns, roads, railways, canals and village-level development. Such imagery is also used to check whether public works have actually been built where they were meant to be.

Fishing, forests and the environment

Oceansat data helps fishermen reach productive waters, saving fuel and time. Forest departments track forest cover, fire hotspots and encroachment, while scientists monitor glaciers, wetlands and coastlines over many years.

Security and strategic needs

Imaging satellites with fine resolution and radar capability support border surveillance and coastal monitoring, and dedicated communication satellites serve the armed forces. This is a sensitive area, so details are rarely made public, but the role is widely acknowledged.

Disaster management

During floods, earthquakes, landslides and forest fires, authorities use satellite images to assess damage within hours, and communication satellites restore links where ground networks have failed.

Satellite Families at a Glance

The table below summarises the main groups of Indian satellites, their purpose and the typical orbit in which they operate.

The Economics: NSIL, Antrix and Commercial Launches

Space is not only a public service; it is also a business. ISRO’s commercial arm, Antrix Corporation, was set up in 1992 to market Indian space products and services. In 2019, a new public sector company, NewSpace India Limited (NSIL), was established under the Department of Space to take a larger role in commercialising technologies and running production and launch services.

The best-known business is launching foreign satellites. Over the years, PSLV has carried a large number of satellites belonging to other countries and companies, typically small and medium-sized ones, to orbit. Customers come from Europe, North America, Asia and elsewhere. India has a reputation for reliable launches at comparatively low cost, which keeps these customers returning.

• Launch services: a ride to orbit on PSLV or other vehicles for domestic and foreign customers.
• Satellite building: manufacturing of satellites and subsystems, with industry partners increasingly in the lead.
• Data and services: satellite imagery, transponder capacity and ground support.

The model also saves foreign exchange: capacity on Indian satellites replaces what the country would otherwise have to lease from foreign operators.

Opening Up Space: IN-SPACe and Private Players

For decades, space in India was almost entirely a government affair. That changed in 2020, when the government opened the sector to private companies and created the Indian National Space Promotion and Authorisation Centre, known as IN-SPACe. It acts as a single-window agency that authorises, guides and supports private participation, including access to ISRO’s facilities and expertise.

What private companies are doing

• Satellite start-ups: companies building small imaging, communication and data satellites, including hyperspectral imaging and Earth-observation constellations.
• Launch start-ups: firms developing small rockets; in 2022, Skyroot Aerospace flew Vikram-S, the first privately built Indian rocket to reach space on a sub-orbital flight.
• Component makers: small and medium companies supplying electronics, structures and ground systems.

The goal is not to replace ISRO but to let it focus on deep-space missions, human spaceflight and advanced research, while industry takes on routine manufacturing and services. The expected benefits are more jobs, wider use of satellite data and a stronger Indian share in the global space market.

Why Self-Reliance in Space Matters

India’s first satellite needed a foreign rocket; its first rocket-launched satellite did not. That shift from dependence to independence is the heart of the story. Controlling the whole chain, from designing a spacecraft and building a launcher to operating the ground network, gives the country resilience.

It means that communication lines, weather warnings, mapping data and navigation signals are not hostage to another government’s decisions. It also means that Indian scientists, not distant suppliers, set the priorities, whether that is a better monsoon forecast, an accurate map of a village or tracking a threatening cyclone.

From a 1975 spacecraft carrying a handful of experiments to a vast fleet serving farmers, fishermen, broadcasters and the armed forces, Indian satellites have grown into an essential part of national infrastructure. The next chapter, with private firms, small satellites and heavier communication spacecraft, promises to be just as transformative.

Frequently Asked Questions

Which was India’s first satellite?

Aryabhata was India’s first satellite. It was built in India and launched on 19 April 1975 on a Soviet launch vehicle. It carried experiments in X-ray astronomy, aeronomics and solar physics.

What is the difference between INSAT and IRS satellites?

INSAT (and the later GSAT series) are communication and meteorological satellites in geostationary orbit, serving television, telephony, broadband and weather watching. IRS satellites are Earth-observation satellites in lower polar orbits that take images of land, water and forests for mapping, agriculture and resource management.

Which was the first satellite launched by an Indian rocket?

Rohini RS-1 was the first satellite launched by an Indian rocket. SLV-3 placed it in orbit from Sriharikota on 18 July 1980, making India one of the few countries with independent satellite-launch capability.

How do Indian satellites help in cyclone forecasting?

Meteorological satellites such as the INSAT-3D family capture frequent images of clouds, temperature and humidity over the Indian Ocean. Forecasters use them to detect a developing cyclone, track its path and intensity, and issue warnings that help authorities evacuate people from coastal areas in time.

What are NavIC and GAGAN?

NavIC is India’s own regional satellite navigation system that provides positioning and timing over India and the surrounding region. GAGAN is a satellite-based augmentation system that improves the accuracy and reliability of navigation signals over Indian airspace, mainly for aviation.

Can private companies build and launch satellites in India now?

Yes. Since the space sector was opened in 2020, private firms can build satellites, develop rockets and offer space services under the guidance and authorisation of IN-SPACe. ISRO and NSIL continue to run major missions and commercial launches alongside them.

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