How does satellite internet work?

The Hindu

4 days ago

In today's increasingly digitised world, internet connectivity is an absolute necessity, across both military and civilian domains. With Elon Musk's Starlink about to make its debut very soon in India, internet infrastructure is going to fundamentally change.
Why do we need satellite internet?
Ground-based networks use cables and towers. They are the most common form of internet provision, especially in densely populated urban areas. However, they have some limitations. Their reliance on physical infrastructure makes them economically unviable in sparsely populated regions. They are also vulnerable to disruptions from natural disasters such as floods and earthquakes. Furthermore, they often cannot meet the demand for on-the-go connectivity in remote locations or for temporary operations.
Satellite internet emerges as a powerful solution to these challenges. Functioning on a global scale, it provides extensive and resilient coverage. This coverage functions regardless of terrain or the presence of terrestrial infrastructure. It can be deployed rapidly to manage sudden demand surges, and also provides connectivity within moving platforms like airplanes and remote sites such as offshore oil rigs. Thus, satellite internet is not merely a backup system. It is a transformative technology with the potential to reshape the digital economy, civil infrastructure, and military strategy.
What are the features of satellite internet?
The advent of satellite mega-constellations such as Starlink signals a new era in space-based internet. These comprise hundreds or even thousands of satellites orbiting a few hundred kilometres above Earth. This 'internet in the sky' offers a plethora of applications in military operations, disaster response, healthcare, agriculture, and transportation. However, this technology has a dual-use nature, serving both civil and military ends. This introduces complex security dynamics.
Contemporary events underscore this technology's profound impact. When Hurricane Harvey struck the Texas coast in 2017, it knocked out 70% of cell towers in affected regions. Viasat's satellite internet became a lifeline for coordinating rescue operations. Similarly, in the Russia-Ukraine war, SpaceX's Starlink has been pivotal for Ukrainian defence forces. They have relied on it for coordinating troop movements, medical evacuations, and drone operations. Ukrainians even fitted Starlink devices on drones to bypass Russian jamming systems. Satellite internet also enhances operational readiness in isolated conflict zones, as shown by the Indian Army's use of it on the Siachen Glacier. Conversely, its borderless nature facilitates illicit use. Security forces in India have confiscated smuggled Starlink devices from insurgent groups and drug rackets. These instances reveal that control over satellite internet infrastructure is becoming a new dimension of national power.
How does satellite internet work?
A satellite internet network is composed of a space segment and a ground segment. The space segment consists of the satellites in orbit, while the ground segment includes all equipment on Earth that communicates with them. The satellites are the most capital-intensive component. They carry communication payloads for data transmission and have a service life of five to 20 years. Their deployment requires careful planning, especially concerning orbital altitude, which determines the satellite's capabilities and coverage. Satellites are deployed in three main orbits: the Geostationary Earth Orbit (GEO), the Medium Earth Orbit (MEO), and the Low Earth Orbit (LEO).
What are differences between satellites deployed in different orbits?
GEO satellites orbit at 35,786 km above the equator. They match the Earth's rotation, allowing them to remain stationary relative to a point on the ground. This high altitude allows a single GEO satellite to cover nearly one-third of the Earth's surface, though not the polar regions. Viasat's Global Xpress (GX) system is a notable example. GEO satellites are also typically large. They act as 'bent-pipes,' simply relaying signals back to Earth without processing them. Their significant drawback is high propagation latency. The long distance signals must travel result in delays, making GEO systems unsuitable for time-sensitive applications like video conferencing or real-time transactions.
MEO satellites operate at altitudes between 2,000 km and 35,786 km. They offer a compromise between GEO and LEO systems. Their latency is lower than that of GEO satellites, but they still require a constellation for global coverage. The O3b MEO constellation, for instance, consists of 20 satellites. However, their latency is often insufficient for many real-time applications, and the satellites remain large and costly to launch.
LEO satellites orbit at altitudes below 2,000 km. Their proximity to Earth results in very low latency. They are also smaller, often table-sized, making them cheaper and quicker to deploy. Their main disadvantage is their smaller coverage area. A single Starlink LEO satellite's footprint is comparable to an Indian metropolitan city. To achieve global coverage, LEO systems form 'mega-constellations'. These are networks of hundreds or thousands of satellites working in unison. Starlink has over 7,000 satellites in orbit, with plans for up to 42,000.
How do mega-constellations work?
LEO mega-constellations leverage their numbers to turn limitations into strengths. The smaller satellites are capable of on-board signal processing. This enhances data transmission efficiency, improves signal quality, and allows for greater flexibility. This on-board intelligence simplifies the user terminals on the ground. Terminals become smaller, cheaper, and more accessible to individual households.
A key innovation was the use of optical inter-satellite links. These allow satellites to communicate directly with each other in space. This creates a true 'internet in the sky,' an interconnected blanket of satellites. This network can route data globally with minimal reliance on ground stations, reducing latency and increasing efficiency. However, maintaining continuous connectivity is a challenge. LEO satellites move at nearly 27,000 km per hour. They stay within a user's line of sight for only a few minutes. To ensure uninterrupted service, the network must seamlessly 'hand-off' the connection from one satellite to the next. This is achieved with steerable antennas that can track multiple users and ground stations simultaneously, much like moving spotlights on a stage.
What are the applications of satellite internet?
For the end-user, modern LEO satellite internet is a major advancement. User terminals are now compact and easy to set up without professional help. However, the service is still more expensive than terrestrial broadband. While terminals cost around $500, and monthly services start at about $50, the cost is often justified for those in remote areas or in industries where connectivity is paramount.
The future promises even greater accessibility. Companies like AST SpaceMobile and Starlink are testing direct-to-smartphone services. This innovation could eliminate the need for separate user terminals altogether. As the technology becomes mainstream, specialised hardware may be integrated directly into devices like smartphones and laptops.
The applications for satellite internet are vast and transformative. In communications, it provides network access to remote areas and enables the Internet of Everything (IoE). In transportation, it will enhance navigation systems, support self-driving cars, and improve logistics. In public administration and disaster management, it can power smart cities, provide early warnings, and coordinate rescue efforts. The healthcare sector can benefit from telemedicine and remote patient monitoring. Agriculture can leverage it for precision farming and crop health analysis. It also has significant applications in environmental monitoring, energy exploration, tourism, and defence.
Therefore, satellite internet presents immense opportunities but also creates complex security and regulatory challenges. Nations now recognise satellite internet as a new dimension of power.
It is imperative for countries like India to develop comprehensive strategies to integrate the technology into national resilience plans. India should also leverage it to bridge the digital divide and foster economic development. Finally, active participation in shaping its international governance is crucial as these mega-constellations will define the next era of global connectivity and strategic advantage.
Ashwin Prasad is with the Takshashila Institution.