The Earth currently has more than 4,500 active satellites circulating the planet, but only 159 of those operate in medium-Earth orbit (MEO). While MEO certainly has its place in the sky, the orbit has historically featured less satellite traffic than its counterparts in GEO and LEO.

MEO finds itself in an exciting location, offering better latency than GEO satellites and greater ground coverage than LEO. This Goldilocks zone could see increased use in the future as satellite companies look to diversify uses for MEO satellites in innovative ways.

What is Medium-Earth Orbit?

MEO satellites orbit between 10,000 and 20,000 kilometers above Earth.

Despite its lower traffic than other orbits, MEO hosts one of the most well-known satellite commercial uses: GPS. The US Global Positioning System, now under the purview of the U.S. Space Force, operates a constellation of 24 operational satellites at an altitude of approximately 20,200 kilometers. These satellites each circle the Earth twice per day in semi-synchronous orbit.

To ensure the GPS operates at least 95% of the time, the Space Force currently has 29 satellites in orbit as a precaution. In the past, as many as 31 satellites have been in orbit for GPS at one time.

MEO is also home to satellite constellations for Galileo, GLONASS, and BeiDou, the respective European, Russian and Chinese versions of GPS.

Along with these navigation satellites, businesses and government organizations use MEO to enhance communication to parts of the planet at higher latitudes. This includes parts of Northern Russia, Canada and Alaska, among others. The Molniya orbit allows for a stronger signal to be sent to areas in a high latitude where the GEO signals sent to the rest of the world struggle to reach.

The angle of satellites in a Molniya orbit allows for coverage in these areas. These satellites can provide communications support, weather monitoring and early warning systems.

The Growing Use of MEO

Commercial businesses traditionally focus on LEO and GEO business models, with only a handful of companies operating in MEO. However, that could change as network connectivity begins to evolve.

The traditional GEO constellations already provide broadband to consumers, but the existing technology has become too slow by today’s standards. As a result, satellite companies will look more to MEO to provide a stronger signal while lowering latency. There are many applications for this type of service, including high-speed automated trading or gaming. That could happen in one of two ways: First, with MEO constellations directly providing connectivity or using satellites in MEO to support those in LEO.

There has been much talk about the use of MEO lately, especially at Euroconsult’s World Satellite Business Week in December of 2021, where major satellite providers discussed the idea of multi-orbit satellite constellations. The concept is to connect satellites in GEO with those in LEO or MEO to provide more efficient service across the globe, essentially offering customers the benefits of both orbits. The multi-orbit concept can take advantage of the strengths of each systems, using LEO for latency sensitive application and GEO for non-latency sensitive applications.

“The dominant issue is not so much the amount of gross capacity but the efficiency of your ability to deliver that capacity in the places where there’s demand,” said Mark Dankberg, chairman of Viasat. “We’re a believer in multi-orbit because of the latency factor.”

GEO has fundamentally lower cost structure than LEO, and LEO has better latency, so MEO acts as the in between on both.

Growing communication needs will likely expand the use of MEO in the immediate future. However, the profitability of companies providing these upgraded communications offerings in MEO is still yet to be proven.

Companies Operating in MEO

The number of companies with satellites in MEO continues to grow. Here are some of the most prominent companies and projects operating in the space or with stated plans to do so soon.

SES: By far the most significant player, Luxembourg-based SES operates the O3b MEO constellation that provides high-speed Internet service across the globe. SES took control of this satellite constellation after acquiring O3b Networks in 2016. SES is currently the only high-throughput satellite system for internet services to use MEO.

SES has long-planned a successor to the O3b MEO, named mPower. Expected to launch in early 2022 and be operational by mid-year, this upgraded satellite constellation will deliver even faster internet service speeds and feature must higher throughput.

SpaceLink: Based in the United States, SpaceLink plans to use a constellation of four satellites in MEO that would provide satellites in LEO with continuous coverage and immediate download capabilities. Satellites in LEO fly fast and can only upload data when in the range of a ground station. SpaceLink’s design would allow data to be first sent to MEO satellites then relayed to LEO units without delay.

Mangata Networks: Also based in the United States, Mangata recently raised $33 million in venture capital. The company plans to build a constellation of 791 satellites spread across MEO and HEO. These satellites aim to provide network connectivity with high availability and lower latency than existing systems in either underserved or poorly served by existing terrestrial and satellite networks.

Viasat and Intelsat: Both companies have filed for MEO constellations with the Federal Communications Commission. Viasat was approved in 2020 and has six years from that date to put half its constellation in orbit and then another three years after that to have its full system operational.

Isotropic Systems: A developer of multi-link satellite technology, Isotropic Systems has tested multi-orbit antenna trials for the US military and its allies. The company recently demonstrated that its antenna can receive signals from both LEO and MEO satellites. By leveraging multi-orbit satellites, the company can ensure military organizations remain connected in challenging conditions.

Methera Global: UK based, Methera plans to launch 128 Ka-band satellites into four inclined MEO planes. At high altitude MEO, the Methera satellites move relatively slowly - only two orbits per day - enabling tracking with low-cost user terminals. All satellites beams are continuously steerable beams so that anywhere on Earth, irrespective of latitude, is always visible. Methera is offering super-fast broadband for small communities, for emergency/restoration, and for specialist applications in locations which are otherwise underserved.

Government of India: In 2019, India announced plans to build a constellation of communications satellites in LEO and MEO. The goal is to provide improved connectivity to the country’s citizens with reduced latency. It is believed to be the first government program to use satellite constellations for public connectivity.

The Future of MEO

As satellite companies continue to broaden service operations, MEO will be used more and more. The satellites in that orbit provide some of the benefits of both LEO and GEO that have yet to be fully explored. While the future remains slightly uncertain, there is growing excitement around MEO and its potential in the satellite ecosystem.