Low, medium and geostationary orbit: what changed, and why GEO didn't die

In this article I share three things satellites do for the infrastructure we use every day: communication, geolocation and time control. No prior knowledge required. By the end, you will tell low, medium and geostationary orbit apart by the problem each one solves, understand why an entirely terrestrial network still depends on space, and leave with the questions worth asking before contracting orbital capacity.

A satellite communication system should not be chosen by the vendor’s name or by whichever technology is in fashion. Orbit is one of the fundamental architectural decisions, because it determines three things at once: how long the signal takes to travel out and back, how many satellites are needed for continuous coverage, and how the service can be controlled when something goes wrong.

The three altitudes

The altitude at which a satellite operates is not merely an orbital characteristic: it defines much of the architecture, the performance and the economics of the service it can offer. The closer to Earth, the lower the latency — the time needed to send and receive data — and the smaller the area each satellite covers. The farther out, the wider the coverage, but also the higher the latency. It is from this trade-off between latency, coverage, satellite count and constellation complexity that three broad operating models emerge: LEO, MEO and GEO.

Low Earth Orbit (LEO) satellites sit roughly between 300 and 2,000 km up. The signal path is far shorter than in higher orbits, allowing latencies close to those of many terrestrial networks and making the difference barely noticeable for most applications. The price is that each satellite sees a relatively small slice of the planet and moves quickly relative to the surface — continuous service requires a constellation of many satellites.

That scale stopped being a plan some time ago. In August 2026 there were 11,102 Starlink satellites in orbit, 11,087 of them operational — more than half of all active satellites on the planet. Amazon’s Kuiper has around 365 production satellites in orbit and is already one of the largest constellations being deployed. China runs two large programs at once: Guowang, with roughly 190 satellites launched and some 13,000 planned, and Qianfan, also known as Thousand Sails, with 126 in orbit. Together, the two Chinese projects foresee more than 29,000 satellites by the mid-2030s.

Medium Earth Orbit (MEO) satellites generally sit a few thousand to tens of thousands of kilometers out. They are the middle ground: higher latency than LEO, lower than GEO, and far fewer satellites needed to cover the same region. This is where the major satellite navigation systems operate — GPS, Galileo, GLONASS and BeiDou — and where SES, of Luxembourg, built the O3b mPOWER constellation, aimed at enterprise customers, governments, mobile networks and mobility applications.

Geostationary Orbit (GEO) satellites sit at roughly 35,786 km above the equator. At that position, the satellite completes one revolution around the Earth in the same period the planet takes to rotate on its own axis. To an observer on the ground, it appears to stay fixed in the sky, always over the same region. That allows a fixed antenna to be pointed once and stay connected to the same satellite.

A single GEO satellite can cover a continental area, and three well-placed satellites reach most of the planet. The trade-off is distance: latency runs to hundreds of milliseconds. That is poor for interactive applications highly sensitive to delay, and perfectly acceptable for many services where coverage, availability, predictability and control matter more than a few tenths of a second.

The other space infrastructure: position and time

Not every critical satellite exists to carry a user’s communication. An essential part of modern infrastructure depends on satellites whose job is to tell us where we are and, above all, what time it is.

These are the global navigation satellite systems, known by the acronym GNSS: GPS, from the United States; Galileo, from the European Union; GLONASS, from Russia; and BeiDou, from China. Their constellations operate mostly in medium orbit and provide three closely related services: positioning, navigation and timing — PNT.

Positioning is the best-known use. It is what lets a phone determine its location, an aircraft know its position or a ship navigate far from shore. For critical infrastructure, though, the least visible service may also be one of the most important: precise time.

Every GNSS satellite carries atomic clocks and transmits signals that let receivers on the ground obtain an extremely precise time reference. A telecommunications site, an electrical substation or a data center can therefore synchronize its equipment against a global reference without maintaining an atomic clock of equivalent precision locally.

This matters because many distributed networks must agree not only on the data but on when each event happened. Telecommunications networks synchronize sites and equipment; power systems use common time references for measurement, protection and event analysis; financial markets must order transactions; data centers, networks and security systems depend on coherent time records.

There is formal evidence that this dependency is taken seriously outside the technical sector: Executive Order 13905, signed in the United States in February 2020, defines “responsible use of PNT” and directs the government to make available a source of Coordinated Universal Time independent of GNSS for critical infrastructure operators. The NIST PNT program was created to support that directive.

Which means dependence on space infrastructure goes well beyond communication links. Even an entirely terrestrial network may quietly depend on satellites to know where it is and, above all, when each event happened.

What low orbit actually changed in telecommunications

For most of the inhabited planet, “unconnected location” has stopped meaning technical impossibility of connectivity. There are places where connecting remains expensive, difficult, poorly regulated or politically contested — but that is a different problem.

Low orbit changed the relationship between geography and telecommunications. Mountains, forests, long distances and low population density still make terrestrial networks harder or costlier, but they no longer necessarily represent an absolute barrier to offering connectivity.

In Brazil this already shows up in regulation, with numbers attached. In July 2026 Anatel approved changes to Starlink’s operation in the country, clearing the way for an additional 7,500 satellites. And it authorized China’s SpaceSail to operate in the Brazilian market with up to 324 low-orbit satellites by 2031, introducing another large LEO system into the contest for coverage over national territory.

Note what that means: constellations tied to different technological and geopolitical poles can compete to provide service over the same territory. The question stops being satellite versus fibre and starts to include which space networks, operators and jurisdictions will take part in a country’s communications infrastructure.

Why GEO didn’t die

If low orbit solves latency and coverage so well, why does Brazil remain interested in a new geostationary satellite?

Because the question a GEO satellite of your own helps answer is not only “how do I connect everyone?” It is also: “what keeps working under my own decision when I need it to?”

SGDC-1, launched in May 2017 from Kourou, French Guiana, has capacity on the order of 58 Gbps. Part of that capacity, in X band, is dedicated to strategic and defense communications; the rest, in Ka band, is operated by Telebras for telecommunications services. The project cost the public purse R$ 2.78 billion, financed by FINEP, against an initial budget of R$ 1.1 billion — and it was designed for a service life on the order of fifteen years, which puts it in its final third of operation from 2027 onwards.

But the Brazilian plan was never supposed to end at a single satellite. In strategic infrastructure the old redundancy maxim applies: whoever has one has none. The Main Space Operations Center (COPE-P), built to control SGDC, was itself designed to operate more than one geostationary satellite, within an architecture prepared for expansion.

The logic, then, was always to move from SGDC — one satellite — to a Defense and Strategic Communications Satellite System (SSDC), in which capacity, continuity and redundancy would not depend on a single asset in orbit. That design is expressly recorded in the Brazilian Ministry of Defense’s Strategic Space Systems Program (PESE), MD20-S-01, 2nd edition/2025. The document provides that continuity of the service SGDC-1 provides today may come through a second geostationary satellite — SGDC-2 — or even through a constellation in lower orbits, together forming the SSDC.

That is the context in which SGDC-2 appears. Under the design Telebras put out for market consultation, the new system anticipates up to 100 Gbps and preserves requirements of asset ownership, operational control, baseband control and an orbital position associated with Brazil, while integration with other orbital systems is under discussion. The market consultation closed on 15 September 2026 and contracting is expected from 2027. As the process is still under way, schedule, final capacity and contracting model need to be followed as the stages conclude.

The design that matters: multi-orbit

The most relevant point in the Telebras design is not any single satellite. It is the architecture.

The idea is to combine a GEO satellite under Brazilian control with LEO and MEO capacity supplied by third parties. The owned GEO serves the functions for which national control, availability and predictability are central requirements — strategic and defense communications among them — while low and medium orbit constellations can serve what demands scale, mobility or lower latency, such as schools, health posts, remote localities, corporate networks and other distributed applications.

In the intended arrangement, the Space Operations Center remains the central element of the control architecture.

Translated into boardroom language: the question is not simply whether to buy a satellite; it is where the point of control sits.

You can contract capacity from different constellations around the world. What has to be deliberately settled is who controls the operation, who knows the topology, where the gateways are, which components remain under national jurisdiction, and who can decide, in a critical situation, what keeps running.

What to do with this

For anyone operating critical infrastructure, satellite communication should not be treated as a simple connectivity purchase. The choice of orbit, operator and architecture defines not only performance and cost but also dependency, capacity to react and continuity under adverse conditions.

The core point is to design the solution starting from what has to remain available — and from how much control the organization needs to retain when the scenario stops being normal.

Choose the altitude by the requirement, not by the vendor. LEO, MEO and GEO are not competing technologies in every case; they are different answers to different problems. Low latency and broad reach favor LEO. Wide coverage, fixed terminals and predictability remain important advantages of GEO. MEO occupies the middle ground, combining extensive coverage with better performance than geostationary in certain scenarios. In critical architectures, the answer may not be to choose one, but to combine orbits.

Treat the points of control as part of the architecture — and of the contract. Asking how many megabits will be delivered is not enough. You need to know where the gateways are, who operates the ground network, where the control centers sit, under which jurisdiction the assets and the data fall, who can change traffic priorities, and what happens in a political, commercial or military crisis. The more critical the communication, the less acceptable it is to discover those answers after signing.

Do not confuse redundancy with diversity. Two terminals, two links or even two satellites may still depend on the same constellation, the same gateway, the same operator or the same ground infrastructure. That is equipment redundancy, not necessarily resilience.

The more useful question is: how many genuinely independent paths exist between origin and destination?

In critical systems, diversity may mean distinct operators, distinct orbits, distinct ground networks and, when necessary, distinct jurisdictions.

Ultimately, the most resilient architecture is the one that avoids turning any technology, vendor or orbit into a new single point of failure. The satellite then stops being merely an alternative means of access and becomes part of a broader strategy of continuity, control and resilience of communications.