India’s GSAT-11 is one of the heaviest communication satellites ever built by ISRO.
What does a Heavy Satellites Explained?
First, it’s important to define what “heavy” means. In the context of satellites, there are three main parameters: launch mass, satellite bus mass, and payload mass (such as transponders, antennas, engines, etc.). Recent communication satellites being built in India have weighed 3-5 tons or even more. For example, GSAT-11’s launch mass was approximately 5,854 kg.
Why are satellites made heavy? — An analysis of the technical reasons
Here, we’ll examine the technical reasons that increase satellite mass. More transponders and high-throughput payloads are increasingly being used in communications satellites today as demand for broadband internet, satellite TV, in-flight internet, remote connectivity, etc.
Use of Large Antennas/Reflectors and Spot Beams
Satellites are now using “spot beams” for mobile users, in-flight internet, remote access, etc.—small beams targeted at specific areas for frequency reuse. This technology significantly increases transponder capacity but also complicates the satellite’s antenna system. For example: “For the proposed HTS system … a 72-beam configuration with a 2.5 m reflector antenna is chosen…” When antennas are larger, or in “unfoldable” configurations (antennas that fold and slide away from the satellite’s surface), their mass increases—requiring structures, mechanisms, motors, etc., which increase the satellite’s size and mass.
Larger Power and Energy Systems As mentioned above, satellites with transponders and spot beams must have sufficient power—that is, larger solar panels, batteries, and power control units. This also increases the satellite’s mass. For example, GSAT-11’s solar power output was approximately 13.6 kilowatts. Fuel and Propulsion: A communications satellite isn’t simply dropped like a stone at launch—it must be delivered to a high geostationary orbit (GEO), maintained there, and its attitude controlled. To achieve this, the satellite requires a liquid propulsion system (liquid apogee motor, thrusters), fuel tanks, and more.
India-Specific Reasons (Indian Context)
We will now examine the reasons why the weight of communications satellites has become a greater problem or characteristic for India. Growing Demand and Service Expansion
In India, there are challenges in providing internet to remote areas, islands, aerial communication, maritime areas, etc. Connectivity needs to be enhanced. For example: Satellites like GSAT-20 will also provide “in-flight internet” or service “islands and the rest of the Indian region”. For example: The Master Control Facility website states that GSAT-18 was launched from GTO (Geostationary Transfer Orbit) to GEO. India, due to its large service area (India + islands + extensive content), is building larger satellites.
When satellites reached the 4-5 ton range, this limitation became a challenge – for example, GSAT-20 weighed 4,700 kg, which could not be carried by LVM3, so a partnership was formed and it was launched by SpaceX’s Falcon 9. This launch vehicle limitation is the “official reason” that satellites are getting heavier (because payloads have increased) but launch vehicle capacity hasn’t increased at the same pace. Self-reliance and Technological Advancement India has long worked towards “self-reliance”—more and more manufacturing in India, more electronics, more indigenous propulsion systems, etc. For example, GSAT-19 had Indian lithium-ion batteries, fiber-optic gyros, micro electro-mechanical systems (MEMS), etc.
What challenges does “going heavy” bring?
When a satellite becomes heavier, it brings with it several challenges—technical, economic, launch-related, and strategic. Let’s look at it: Launch costs increase. A heavier satellite means more rocket thrust, more fuel, more safety and testing—all of which increase launch costs. If launch vehicle capacity is lower, dependence on foreign rockets increases, increasing costs. For example, India had to use SpaceX for GSAT-20. Lack of a launch vehicle/limitation
As mentioned above: the LVM3 has a launch capacity of approximately 4 tons to GTO; if the satellite becomes heavier than that, it will either require lightening the satellite, developing a better rocket, or seeking foreign services. This poses a challenge for India both strategically and commercially. “The satellite is 4,700 kg and is too heavy for ISRO’s own rockets. … The LVM-3 is capable of launching only a 4,000 kg spacecraft into the Geosynchronous Transfer Orbit.”
Demands for Reliability and Lifespan: Longer satellite lifespan means significant design changes—additional propulsion, additional battery capacity, better thermal control, and improved structure. All of these add weight, but taking these lightly could lead to premature satellite failure or increased risk of failure. System complexity and risk When the payload is very complex (multi-band, spot beam, high transponder count, in-flight internet, etc.) — satellite design becomes complex, testing becomes difficult, costs increase, and the risk of failure also increases. Heavy satellites pose a technological challenge to India. Competitive and strategic pressures Building heavy satellites signals that the country is playing a “key role”—but it also creates pressure that each new satellite must be “better than the previous one,” not lagging behind. Failure to maintain capabilities can pose strategic and commercial challenges.
India’s Situation: Benefits and Opportunities
While there are challenges, heavy communication satellites also have some clear benefits and opportunities for India. Wider Service Area: Heavy satellites can carry more transponders, more power, and more spot beams—the advantage of which is that wider service can be provided to all of India (and islands and coastal areas). For example, GSAT-18/GSAT-11, etc., strengthen India’s position as a service provider. Self-reliance—developing an indigenous satellite system—means India will be less dependent on foreign launches or technology. For example, the launch of CMS-03 demonstrated that India has upgraded its launch vehicle.
Commercial Opportunities Once large communication satellites are built, it will be possible to expand broadband services, in-flight internet, internet access to remote areas, social services, and more—which will increase commercial opportunities. Satellites like GSAT-20 are working in this direction. Strategic and Defense Uses In India, communication satellites are not just commercial but also useful in defense communications, maritime communications, long-range coverage, and more. For example, the CMS-03 satellite was built for the Indian Navy.
What is the Solution? — The Way Forward
Despite the challenges of heavy satellites, there are some strategic options for the future that can achieve load management, cost management, and capacity enhancement. Small and Medium Satellites: Instead of heavy geostationary satellites, India could look at small or mid-sized satellites for specific service areas. This model is being implemented in some countries through the “Lease/Cluster” model. This is the suggested change of approach. Energy-propulsion innovations (Electric propulsion, lighter materials)—for example, electric thrusters, lightweight structural materials, and lightweight propulsion systems—can help make satellites lighter. There are some indications that India is working in this direction.
Increasing Launch Vehicle Capacity: India needs to enhance its launch vehicle (next-generation after LVM3) capabilities to be able to launch satellites weighing more than 4-5 tons without the use of foreign rockets. As CMS-03 demonstrated, the LVM3-M5 has improved. Modular Design and Shared Missions: Making satellites modular, where payloads can be changed as needed, and adopting shared mission models (with other users/countries) can reduce both cost and weight. Planning, Management, and Cost Estimation: Satellite construction should have clear cost estimates, lifetimes, and service models in place—so that “making it heavy” is not just a technical exercise but makes economic and service sense.
Conclusion: Heavy Satellites Explained
In short, India’s communication satellites are becoming heavier because the service sector is expanding, payloads are becoming more complex, and technical requirements have become higher. Furthermore, launch vehicle limitations, the desire for self-reliance, and industry strategy are driving this direction. However, “heavier = better” doesn’t always mean “heavier = better”—this can become a risk if satellite manufacturing and launch costs become too high, or launch vehicles are unavailable, or the satellite service model is ineffective. India must further strike that balance: high capacity + reasonable weight + affordable cost + reliable service. Building heavier satellites means India has achieved advanced technology—but the question now is how to maximize the “benefit” of this heaviness—is it service-capable, is it commercial, is it strategic?
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