What are the differences between LEO and GEO satellites?

Over the years there has been a continuous debate across different users of satellite communications about whether Low-Earth Orbit (LEO) or Geosynchronous Equatorial Orbit (GEO) satellites are more effective at providing communications. With AST’s 30 years of experience in the sector we can outline how each constellation architecture works, their key differences and how their key strengths support different uses.

What are GEO satellites?

GEO satellites work in a geostationary orbit. It is a circular geosynchronous orbit 36,000 kms above the Earth’s equator (or alternatively 42,000 kms radius from the Earth’s centre) following the direction of the Earth’s rotation and takes 24 hours.

Communications satellites in this orbit are fixed above a single point which means that an antenna on Earth does not have to track or rotate but can be pointed permanently at the known position in the sky, despite the satellite actually travelling at 11,300 kms per hour. Satellites require some station keeping in order to maintain position.

The first satellite placed in geostationary orbit was Syncom 3 launched in 1964 and was used to transmit live coverage of the summer Olympics from Japan to the USA. Uses include weather observations, navigation and a huge variety of communications. Intelsat and Inmarsat are two of the better known satellite operators with GEO constellations. 

What are LEO satellites?

LEO satellites work in a low earth orbit. It is an earth-centered orbit close to the planet often specified as an orbital period of 128 minutes making 12 orbits per day. The LEO region is generally accepted to be below 2,000 kms altitude.  Amazingly the mean orbital velocity needed to maintain a stable low earth orbit is about 28,000 kms per hour but reduces with increased orbital altitude.

Unlike GEOs a LEO satellite has a small field of view and so can communicate with only a fraction of the Earth at a time which means that a network is required to provide continuous coverage.

Although the first LEO satellite was launched in the 1950s, it wasn’t until the 1980s that engineers began to challenge the effectiveness of GEO satellites and their architecture (that many LEO satellites had adopted too). That’s when the idea for a LEO satellite constellation first occurred.

What are GEO satellites used for?

Due to GEO’s first mover advantage, the vast majority of communications by satellite are undertaken by GEOs. Each large satellite covers up to one third of the earth’s surface. GEOs do not suffer from intersatellite handoff and are ideal for broadcasting, weather forecasting and satellite radio. GEO satellites provide the backbone of global space communications and continue to be built.

With global communication evolving and demands increasing for uninterrupted low latency communication anywhere in the world, the fixed nature of GEO satellites limits its ability to provide that type of service.  For example if reception is required in an east/west canyon a single GEO satellite may be blocked by a mountain.

What are LEO satellites used for?

LEO satellites provide true global coverage with low latency typically more than five times faster than GEOs, making the user experience more akin to terrestrial fibre connected devices. For this reason, many critical communications are handled over LEO satellite networks, which allow for faster connectivity without wires or cables.

The look angles from an overhead satellite avoids directional obstruction problems since LEO satellites are always moving. The chances of a long or persistent signal blockage are greatly reduced.

The growing LEO satellite communication industry

LEO terminals have inherently been more complicated and expensive to produce when compared to GEO terminals, as they must be able to passively or actively track fast moving satellites.

That cost is starting to be driven down as demand grows for true global internet connectivity  and the potential benefits and uses of low latency/high speed connectivity begins to be realised.

How many LEO satellites cover the earth?

In total there 11,102 LEO satellites covering the earth all providing different connectivity uses for a variety of global industries.

A visualization of the number and complexity of LEO satellites provided by LeoLabs.

leo satellites

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Reducing shipping emissions – how can satellite technology help?

shipping co2 emissions

We often hear in maritime circles the well versed but still startling fact: if ocean shipping were a country, it would be the sixth-largest carbon emitter, releasing more CO2 annually than Germany. In fact, if we carry on unchecked, global shipping carbon emissions could rise from 3% to 17% of the world’s total carbon emissions by 2050.   

The pressure is on to reduce shipping carbon emissions

The industry already knows it has to address shipping carbon emissions. The pressure is not just the political desire to meet the Net Zero 2050 target – it is coming from all angles.

  • Nine big companies including Amazon, Ikea and Unilever have signed up to a pledge to only move cargo on ships using zero-carbon fuel by 2040. 
  • The impact of ESG (Environmental, social and governance) and major bank lending standards
  • Even employees are beginning to demand credible, standardized information to support long-term assessments of decarbonization. 

Unlike the motor industry where decisions around power technology, future fuels and supply chains has made notable progress over the past 10 years, the global shipping industry infrastructure is still in its infancy due to its complexity and differences of opinion from influential shipping nations.  

Reducing shipping emissions today

Whilst bigger infrastructure changes are being actively pushed for the longer term, connectivity will play a further role in reducing shipping CO2 emissions and our transition to Net Zero.  

Digital transformation and the adoption of smart technology with low-latency, fibre-like satellite connectivity such as OneWeb can have a significant impact on reducing shipping CO2 emissions and meeting national and global regulations. It can allow operators to source essential data at sea by accessing terrestrial-quality speed and a tenfold increase in bandwidth at sea. This digital transformation allows them to analyse data wherever they are in the world, in real-time, in order to inform their environmental strategies. 

Pairing OneWeb’s connectivity with AST’s iRAMS Telematics solutions, provide all maritime vessel operators the opportunity to operate their vessels at peak performance and in turn reduce shipping carbon emissions.  

  • Fuel efficiency – The iRAMS platform can help reduce fuel usage and subsequent costs by 25%. Data highlights any inefficiencies caused by the skipper or vessels behaviour.
  • Environmental monitoring – Dependent on a vessel owners needs,  iRAMS can help monitor such metrics as CO2 emissions, fuel burn rate, engine performance parameters, electrical monitoring, vessel motion etc. With the consistent connectivity provided by OneWeb, all these elements can help identify performance deficiencies on a vessel and reduce energy usage and reduce potential harmful emissions.
  • Remote asset control – iRAMS doesn’t just offer monitoring as a versatile IoT (Internet of Things) application for telematics – it can provide remote asset control, allowing you to potentially address performance deficiencies and adjust controls remotely from anywhere in the world. 

Together we can achieve Net Zero

The scope of what can be measured and managed remotely through AST’s iRAMS platform is greatly accelerated by the fibre-like, low latency connectivity provided by OneWeb.  

As OneWeb’s first and most experienced maritime partner AST are already looking at how our partnership can help the shipping industry make concerted efforts in reducing carbon emissions and help support the wider decarbonization agenda.  

OneWeb White Paper

An economical means of bridging the digital divide – OneWeb White Paper

Some of the most compelling reasons for the satellite and broader aerial connectivity push are clear: the size and persistence of the digital divide, and connectivity barriers for businesses operating in rural or remote areas. It can be easy to forget that on a global scale, mobile internet penetration is only 50%. This means around 3.7 billion people (or 3 billion adults) remain offline, most of whom reside in India, China, Africa and a handful of populous lower-income Asian countries such as Pakistan and Indonesia. OneWeb estimate 25% of this unconnected population – approximately 780 million people – live outside of range of a 3G or 4G signal.

The OneWeb White Paper lays out the case for how the digital divide can be bridged.

Connecting from the sky – Reinventing the final frontier