Geostationary orbit
GEO places a satellite in permanent view of one third of the Earth's surface, making it the default orbit for broadband comms and meteorological imaging. The physics are fixed: 35,786 km altitude, 270 ms one-way latency, and a launch mass bill that concentrates minds.
Why 35,786 km and not a metre more or less
Geostationary orbit exists at exactly one altitude because orbital mechanics demands it. At 35,786 km above the equator, a satellite's orbital period matches Earth's rotation period of 23 hours 56 minutes 4 seconds. The satellite neither laps the planet nor falls behind. From the ground it appears fixed, which is the entire point.
That fixity is enormously valuable. A single GEO satellite illuminates roughly 42 per cent of Earth's surface continuously, with useful elevation angles above about 5 degrees from latitudes up to roughly 75 degrees north or south. Three well-placed satellites can cover almost the entire inhabited world. No other orbit class delivers that geometry without a constellation of dozens of spacecraft.
The slot is the asset, not just the satellite
A GEO orbital slot is a shared international resource coordinated through the ITU Radio Regulations. Filing for a slot requires a national administration to submit coordination documentation, typically years before launch. The ITU's 'due diligence' milestones require a satellite to be brought into use within seven years of the filing date, with specific in-orbit confirmation steps. Miss those milestones and the filing lapses.
For a government entering GEO for the first time, this process is not a formality. Slots in the most commercially attractive arc, particularly over populous regions or prime broadcasting longitudes, are contested. Interference coordination with neighbouring operators is legally required and can take years to resolve. A national administration that has not yet filed has no priority claim. Filing early, even before a satellite design is finalised, is standard practice among experienced operators.
The practical consequence is that the slot filing process and the satellite programme must run in parallel from day one. Treating ITU coordination as a procurement afterthought is one of the most common and costly mistakes a new GEO operator can make.
Mass, power and the launch bill
GEO is expensive to reach. A direct geostationary transfer orbit (GTO) injection requires a launch vehicle to deliver the spacecraft to an elliptical orbit with apogee near 35,786 km; the satellite's own propulsion system then circularises. That apogee kick, or an equivalent electric propulsion sequence, adds propellant mass. A communications satellite capable of meaningful capacity, say a high-throughput Ku- or Ka-band payload, typically arrives at launch in the 3,000 to 6,000 kg class. Some all-electric platforms, such as Boeing's 702SP, reduce that figure by eliminating chemical apogee motors, but they extend orbit-raising time to six months or more, delaying revenue.
Power budgets are generous by satellite standards. Large GEO comms platforms routinely carry 10 to 20 kW of end-of-life power, fed by solar arrays spanning 30 to 40 metres tip to tip. That power envelope supports high-bandwidth transponders, active phased arrays and onboard processing. Smaller GEO meteorological satellites, such as the EUMETSAT Meteosat Third Generation series, are somewhat lighter but still operate in the 3,500 kg launch-mass range with substantial power budgets to run imager and sounder payloads simultaneously.
Latency is not a configuration option
Light travels at roughly 300,000 km per second. The round-trip path from ground to GEO and back covers approximately 71,600 km minimum. The resulting one-way propagation delay is around 270 milliseconds; round-trip is roughly 550 ms before any processing or protocol overhead is added. That figure is a physical constant, not a vendor specification.
For broadcast television, weather data distribution and most government data relay applications, 270 ms is entirely acceptable. For interactive voice, real-time telemetry loops or applications built on TCP protocols that depend on rapid acknowledgement, it is a genuine constraint. Latency-sensitive applications, including certain command-and-control links, require careful protocol design or must consider other orbit options. Honest programme planning acknowledges this from the requirements phase rather than discovering it during integration testing.
What GEO does badly, and when it fails
Coverage geometry has a hard polar limit. Above roughly 75 to 80 degrees latitude, a GEO satellite sits below 5 degrees of elevation, making link margins poor and atmospheric effects severe. Arctic and Antarctic operations simply cannot rely on GEO without supplementary assets.
Sun interference events, known as solar outages, occur twice a year when the sun passes directly behind the satellite from the perspective of a ground antenna. These outages last up to ten minutes per day for several days and are predictable but unavoidable. Operators plan around them with backup links or scheduled downtime.
End-of-life disposal is regulated. ITU and IADC guidelines require operators to manoeuvre retired GEO satellites into a 'graveyard' orbit roughly 300 km above the GEO arc, consuming propellant reserved specifically for that purpose. Failure to budget that propellant at the design stage is not an oversight the regulator will forgive. Finally, a single GEO satellite is a single point of failure. Redundancy requires either a second satellite or a pre-negotiated hosted-payload agreement with another operator, neither of which is cheap.
Where Satellize fits in a GEO programme
Satellize structures GEO engagements around the two things that trip up new national operators most often: ITU slot strategy and sovereign control of the asset once it is on-orbit. Source-access terms, hardware audit rights and staged handover to national operations teams are agreed before contract signature, not negotiated under time pressure after launch.
The Tonga sovereign-comms restoration programme, delivered after the 2022 Hunga Tonga submarine cable break, illustrated the value of having a single accountable engineer across mission architecture, integration and ground infrastructure. GEO programmes are long, expensive and politically visible. The programme management structure matters as much as the satellite specification.
Engineering parameters
| Orbital altitude | 35,786 km (equatorial, circular) |
| Orbital period | 23 h 56 min 4 s (sidereal day) |
| One-way propagation delay | ~270 ms (minimum, nadir path) |
| Typical launch mass (comms) | 3,000–6,000 kg to GTO |
| End-of-life power (large comms) | 10–20 kW |
| Design life (commercial norm) | 15–18 years |
| Coverage per satellite | ~42% of Earth's surface; useful to ~75° latitude |
| ITU filing lead time | Typically 5–7 years before operational date |
| Graveyard orbit altitude | GEO + ~300 km (IADC guideline) |
| Solar outage duration | Up to ~10 min/day for several days, twice yearly |
One contract, one accountable engineer
Commissioned as one programme, not a stack of contracts: spacecraft, launch, ground segment, mission control, training and handover are priced together. Source-access terms and audit rights are agreed in writing before signature. Request a slot-filing readiness review.