O3b Satellite Constellation
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O3b is a
satellite constellation A satellite constellation is a group of artificial satellites working together as a system. Unlike a single satellite, a constellation can provide permanent global or near-global pass (spaceflight), coverage, such that at any time everywhere on E ...
in
Medium Earth orbit A medium Earth orbit (MEO) is an geocentric orbit, Earth-centered orbit with an altitude above a low Earth orbit (LEO) and below a high Earth orbit (HEO) – between above sea level.
(MEO) owned and operated by SES, and designed to provide lower-latency broadband connectivity to remote locations for mobile network operators and internet service providers, maritime, aviation, and government and defence. It is often referred to as O3b MEO to distinguish these satellites from SES's
O3b mPOWER O3b mPOWER is a communications satellite system owned and operated by SES. The system uses high-throughput and low- latency satellites in a medium Earth orbit (MEO), along with ground infrastructure and intelligent software, to provide multip ...
constellation. O3b originally stood for "other three billion", or the other three billion people at the time that did not have stable internet access, and the constellation was initially built, owned and operated by
O3b Networks O3b Networks Ltd. was a network communications service provider building and operating a medium Earth orbit (MEO) satellite constellation primarily intended to provide voice and data communications to mobile operators and Internet service prov ...
, which became a wholly owned subsidiary of SES in 2016 and ownership and operation of the constellation passed to SES Networks, a division of SES. The O3b MEO constellation began offering service in March 2014.


History

Initially planned to launch in 2010, the first four O3b satellites reached orbit on a
Soyuz-2 Soyuz2 (; GRAU index: 14A14) is a Russian expendable medium-lift launch vehicle and the seventh major iteration of the Soyuz rocket family. Compared to its predecessors, Soyuz-2 features significant upgrades, including improved engines and ...
/ Fregat-MT
launch vehicle A launch vehicle is typically a rocket-powered vehicle designed to carry a payload (a crewed spacecraft or satellites) from Earth's surface or lower atmosphere to outer space. The most common form is the ballistic missile-shaped multistage ...
by
Arianespace Arianespace SA is a French company founded in March 1980 as the world's first commercial launch service provider. It operates two launch vehicles: Vega C, a Small-lift launch vehicle, small-lift rocket, and Ariane 6, a Medium-lift launch vehicl ...
on 25 June 2013. After discovering a hardware defect in the initial satellites, O3b postponed the planned September 2013 launch of four additional satellites so repairs could be made. The second four satellites were launched by the same type of rocket from the Space Center in
French Guiana French Guiana, or Guyane in French, is an Overseas departments and regions of France, overseas department and region of France located on the northern coast of South America in the Guianas and the West Indies. Bordered by Suriname to the west ...
, on 10 July 2014 and the O3b system started full commercial service on 1 September 2014. The third launch of four took place in December 2014, bringing the
satellite constellation A satellite constellation is a group of artificial satellites working together as a system. Unlike a single satellite, a constellation can provide permanent global or near-global pass (spaceflight), coverage, such that at any time everywhere on E ...
to 12 satellites. Four years later, four additional satellites were launched on 9 March 2018 on a
Soyuz-2.1b Soyuz2 (; GRAU index: 14A14) is a Russian expendable medium-lift launch vehicle and the seventh major iteration of the Soyuz rocket family. Compared to its predecessors, Soyuz-2 features significant upgrades, including improved engines and ...
rocket from the
Centre Spatial Guyanais The Guiana Space Centre (; CSG), also called Europe's Spaceport, is a spaceport to the northwest of Kourou in French Guiana, an Overseas departments and regions of France, overseas region of France in South America. Kourou is located approxim ...
. In December 2018,
Thales Alenia Space Thales Alenia Space () is a joint venture between the French technology corporation Thales Group (67%) and Italian defense conglomerate Leonardo (company), Leonardo (33%). The company is headquartered in Cannes, France. It provides space-based ...
said that tests on the final four O3b satellites would be completed by the end of January 2019 and the four satellites were successfully launched on 4 April 2019. In 2010, operators in the
Cook Islands The Cook Islands is an island country in Polynesia, part of Oceania in the South Pacific Ocean. It consists of 15 islands whose total land area is approximately . The Cook Islands' Exclusive Economic Zone (EEZ) covers of ocean. Avarua is its ...
,
Pakistan Pakistan, officially the Islamic Republic of Pakistan, is a country in South Asia. It is the List of countries and dependencies by population, fifth-most populous country, with a population of over 241.5 million, having the Islam by country# ...
and
Nigeria Nigeria, officially the Federal Republic of Nigeria, is a country in West Africa. It is situated between the Sahel to the north and the Gulf of Guinea in the Atlantic Ocean to the south. It covers an area of . With Demographics of Nigeria, ...
were among the first to prebook capacity on the O3b constellation to serve their respective markets. In 2010, O3b announced the selection of Europe Media Port to be the first provider of Gateway Teleport services for O3b's global network and a contract with
Viasat Viasat may refer to: *Viasat (American company) (founded 1986) ** Viasat hack, a cyberattack on the Viasat KA-SAT network that happened in February 2022 *Viasat (Nordic television service) Viasat is a direct broadcast satellite, satellite and pa ...
for the production and installation of Ka-band infrastructure. In July 2014, SES Government Solutions (now SES Space & Defense), a subsidiary of (then O3b investor, now owner) SES, received approval to offer O3b services on their
General Services Administration The General Services Administration (GSA) is an Independent agencies of the United States government, independent agency of the United States government established in 1949 to help manage and support the basic functioning of federal agencies. G ...
(GSA) schedule allowing SES GS to be the first distribution partner to offer O3b capability directly to the
U.S. Government The Federal Government of the United States of America (U.S. federal government or U.S. government) is the national government of the United States. The U.S. federal government is composed of three distinct branches: legislative, executi ...
. In November 2014,
MS Quantum of the Seas ''Quantum of the Seas'' is a currently operated by Royal Caribbean International and is the lead ship of her class. At her time of delivery in 2014, ''Quantum of the Seas'' was the third largest cruise ship in the world by gross tonnage. She ...
became the first cruise ship to provide fast internet to guests through O3b Networks. The service is branded "Voom" by its cruise line,
Royal Caribbean International Royal Caribbean International (RCI), formerly Royal Caribbean Cruise Line (RCCL), is a cruise line founded in 1968 in Norway and organized as a wholly owned subsidiary of Royal Caribbean Group since 1997. Based in Miami, Florida, it is the l ...
and it was subsequently rolled out to every ship in their fleet. In August 2015, SES subsidiary, SES Government Solutions (now SES Space & Defense) agreed on a one-year contract with US government scientific agency,
National Oceanic and Atmospheric Administration The National Oceanic and Atmospheric Administration (NOAA ) is an American scientific and regulatory agency charged with Weather forecasting, forecasting weather, monitoring oceanic and atmospheric conditions, Hydrography, charting the seas, ...
(NOAA) to supply O3b services and ground equipment to the
National Weather Service The National Weather Service (NWS) is an Government agency, agency of the Federal government of the United States, United States federal government that is tasked with providing weather forecasts, warnings of hazardous weather, and other weathe ...
Office in
American Samoa American Samoa is an Territories of the United States, unincorporated and unorganized territory of the United States located in the Polynesia region of the Pacific Ocean, South Pacific Ocean. Centered on , it is southeast of the island count ...
, expanding NOAA's broadband connectivity outside the continental United States to provide weather, water, and climate data, and forecasts and warnings to American Samoa. In August 2016, SES Government Solutions (now SES Space & Defense) announced a contract to provide O3b's high throughput, low latency satellite communications for a
US Department of Defense The United States Department of Defense (DoD, USDOD, or DOD) is an executive department of the U.S. federal government charged with coordinating and supervising the six U.S. armed services: the Army, Navy, Marines, Air Force, Space Force, ...
end-user. The agreement is for a 365 days-per-year service consisting of a full-duplex symmetric 155 Mbit/s link, gateway access, a transportable 2.4 metre terminal, terrestrial backhaul, and maintenance and installation services, with a latency of under 200 milliseconds per round trip. The contract also provides for additional capacity to meet surge requirements. In September 2017, SES announced
O3b mPOWER O3b mPOWER is a communications satellite system owned and operated by SES. The system uses high-throughput and low- latency satellites in a medium Earth orbit (MEO), along with ground infrastructure and intelligent software, to provide multip ...
, the next generation of MEO satellites to expand the capacity of the existing O3b constellation of (then) 12 satellites. Initially seven O3b mPOWER satellites were ordered from
Boeing The Boeing Company, or simply Boeing (), is an American multinational corporation that designs, manufactures, and sells airplanes, rotorcraft, rockets, satellites, and missiles worldwide. The company also provides leasing and product support s ...
for launch in 2021 to provide flexible and scalable, low-latency satellite-based networks with terabits of throughput. In June 2018, the
US Department of Defense The United States Department of Defense (DoD, USDOD, or DOD) is an executive department of the U.S. federal government charged with coordinating and supervising the six U.S. armed services: the Army, Navy, Marines, Air Force, Space Force, ...
signed a single-award blanket purchase agreement with SES Government Solutions (now SES Space & Defense) for MEO high throughput, low latency satellite services including managed broadband services, gateway services, and monitoring and control services, to a maximum of US$516.7 million over a five-year period. In September 2019, SES became a
Microsoft Azure Microsoft Azure, or just Azure ( /ˈæʒər, ˈeɪʒər/ ''AZH-ər, AY-zhər'', UK also /ˈæzjʊər, ˈeɪzjʊər/ ''AZ-ure, AY-zure''), is the cloud computing platform developed by Microsoft. It has management, access and development of ...
ExpressRoute services partner to provide dedicated, private network connectivity from sea vessels, aircraft, and industrial or government sites anywhere in the world to the Azure
cloud computing Cloud computing is "a paradigm for enabling network access to a scalable and elastic pool of shareable physical or virtual resources with self-service provisioning and administration on-demand," according to International Organization for ...
service, via both its geostationary satellites and O3b MEO satellites. In August 2020 SES contracted
Boeing The Boeing Company, or simply Boeing (), is an American multinational corporation that designs, manufactures, and sells airplanes, rotorcraft, rockets, satellites, and missiles worldwide. The company also provides leasing and product support s ...
to build four
O3b mPOWER O3b mPOWER is a communications satellite system owned and operated by SES. The system uses high-throughput and low- latency satellites in a medium Earth orbit (MEO), along with ground infrastructure and intelligent software, to provide multip ...
satellites in addition to the seven ordered in 2017.
SpaceX Space Exploration Technologies Corp., commonly referred to as SpaceX, is an America, American space technology company headquartered at the SpaceX Starbase, Starbase development site in Starbase, Texas. Since its founding in 2002, the compa ...
was contracted for additional launches, to make four launches for the whole O3b mPOWER constellation, expected in 2021–2024.''SES taps SpaceX for two additional Falcon 9 launches''
Space News. 20 August 2020. Accessed 27 January 2023
In September 2020, SES and Microsoft announced that SES was the
medium Earth orbit A medium Earth orbit (MEO) is an geocentric orbit, Earth-centered orbit with an altitude above a low Earth orbit (LEO) and below a high Earth orbit (HEO) – between above sea level.
connectivity partner for the Microsoft Azure Orbital ground station service that enables network operators to control their satellite operations and capacity from within the Azure
cloud computing Cloud computing is "a paradigm for enabling network access to a scalable and elastic pool of shareable physical or virtual resources with self-service provisioning and administration on-demand," according to International Organization for ...
service. Under their agreement, SES and Microsoft will jointly invest in Azure Orbital ground stations for the MEO and Earth Observation segments, initially in the United States, which will be installed and managed by SES. Also, satellite telemetry, tracking and control systems and data ground stations for the
O3b mPOWER O3b mPOWER is a communications satellite system owned and operated by SES. The system uses high-throughput and low- latency satellites in a medium Earth orbit (MEO), along with ground infrastructure and intelligent software, to provide multip ...
satellites will be located with Microsoft's Azure edge sites to provide O3b mPOWER customers with "one-hop" access to Azure cloud services. In October 2020, international charity hospital ships provider,
Mercy Ships Mercy Ships is an international charity based non-governmental organization that operates the largest non-governmental hospital ships in the world, providing Christian humanitarian aid, surgical care and surgical education in Africa, community ...
announced it will be using SES's Signature Maritime connectivity services via O3b satellites to provide remote viewing and diagnosis, and remote training on board the Global Mercy, the world's largest civilian hospital ship. In February 2021, SES announced two contracts with the
US Department of Defense The United States Department of Defense (DoD, USDOD, or DOD) is an executive department of the U.S. federal government charged with coordinating and supervising the six U.S. armed services: the Army, Navy, Marines, Air Force, Space Force, ...
as part of the June 2018 blanket purchase agreement. One is for a portable O3b service to support forward-deployed military personnel and the second to provide O3b mission-critical communications without using a commercial gateway in remote locations in Southwest Asia, managed and controlled from an SES Network Operations Center. Also in February 2021, SES announced that its Signature Cruise broadband connectivity via O3b will be used on
Virgin Voyages Virgin Voyages is a cruise line headquartered in Plantation, Florida and a joint venture between the Virgin Group and Bain Capital. As of April 2024, Virgin Voyages has three ships in the fleet, with one more on order, all with an expected c ...
' latest ships Scarlet Lady and Valiant Lady to provide passengers with free fast onboard wi-fi internet access. In June 2021, SES joined the
Amazon Web Services Amazon Web Services, Inc. (AWS) is a subsidiary of Amazon.com, Amazon that provides Software as a service, on-demand cloud computing computing platform, platforms and Application programming interface, APIs to individuals, companies, and gover ...
Direct Connect Delivery Partner programme, using the O3b constellation (and SES' fleet of
geostationary A geostationary orbit, also referred to as a geosynchronous equatorial orbit''Geostationary orbit'' and ''Geosynchronous (equatorial) orbit'' are used somewhat interchangeably in sources. (GEO), is a circular geosynchronous orbit in altitud ...
satellites) to provide customers access to AWS cloud-based applications and services from locations around the world with limited or no terrestrial communications, and to provide the cloud provider a backup network if their infrastructure fails. In August 2021,
Microsoft Microsoft Corporation is an American multinational corporation and technology company, technology conglomerate headquartered in Redmond, Washington. Founded in 1975, the company became influential in the History of personal computers#The ear ...
became the first
cloud In meteorology, a cloud is an aerosol consisting of a visible mass of miniature liquid droplets, frozen crystals, or other particles, suspended in the atmosphere of a planetary body or similar space. Water or various other chemicals may ...
provider customer for O3b, with Microsoft buying managed satellite connectivity services from SES for the
Microsoft Azure Microsoft Azure, or just Azure ( /ˈæʒər, ˈeɪʒər/ ''AZH-ər, AY-zhər'', UK also /ˈæzjʊər, ˈeɪzjʊər/ ''AZ-ure, AY-zure''), is the cloud computing platform developed by Microsoft. It has management, access and development of ...
cloud computing service. Microsoft is initially using the existing first generation O3b satellites, later upgrading to the faster broadband speeds from second generation
O3b mPOWER O3b mPOWER is a communications satellite system owned and operated by SES. The system uses high-throughput and low- latency satellites in a medium Earth orbit (MEO), along with ground infrastructure and intelligent software, to provide multip ...
satellites. In December 2021, SES's wholly owned subsidiary SES Government Solutions (now SES Space & Defense) announced that the US Army has conducted trials of commercial
satellite constellation A satellite constellation is a group of artificial satellites working together as a system. Unlike a single satellite, a constellation can provide permanent global or near-global pass (spaceflight), coverage, such that at any time everywhere on E ...
s in multiple orbits, including the O3b satellite system, as part of the effort to establish Multi-Domain Operations. In December 2021,
Honeywell Honeywell International Inc. is an American publicly traded, multinational conglomerate corporation headquartered in Charlotte, North Carolina. It primarily operates in four areas of business: aerospace, building automation, industrial automa ...
,
Hughes Network Systems Hughes Network Systems, LLC is an American telecommunications company that specializes in providing satellite-based communication services for consumer and enterprise markets. It is headquartered in Germantown, Maryland and provides satellite i ...
and SES demonstrated multi-orbit high-speed airborne connectivity for military customers using Honeywell's JetWave MCX terminal and a Hughes HM-series modem, and SES satellites in both
medium Earth orbit A medium Earth orbit (MEO) is an geocentric orbit, Earth-centered orbit with an altitude above a low Earth orbit (LEO) and below a high Earth orbit (HEO) – between above sea level.
(MEO) and
geostationary orbit A geostationary orbit, also referred to as a geosynchronous equatorial orbit''Geostationary orbit'' and ''Geosynchronous (equatorial) orbit'' are used somewhat interchangeably in sources. (GEO), is a circular orbit, circular geosynchronous or ...
(GEO). The tests achieved full duplex data rates of more than 40 megabits per second via a number of SES' (GEO) satellites including GovSat-1, and the O3b
satellite constellation A satellite constellation is a group of artificial satellites working together as a system. Unlike a single satellite, a constellation can provide permanent global or near-global pass (spaceflight), coverage, such that at any time everywhere on E ...
, with connections moving between GEO/MEO links in under 30 sec. In May 2022, in conjunction with
Kazakhstan Kazakhstan, officially the Republic of Kazakhstan, is a landlocked country primarily in Central Asia, with a European Kazakhstan, small portion in Eastern Europe. It borders Russia to the Kazakhstan–Russia border, north and west, China to th ...
i mobile network operator,
Kcell Kcell (KASE: KCEL) is the Cellular Communication Operator in Kazakhstan, part of Kazakhtelecom. The company was founded in 1998 and provides cellular services under the Kcell brand, which is mainly focused on the corporate segment, and Activ, ...
, SES used the O3b satellite constellation to demonstrate that MEO satellites could be used to provide high-speed 3G and 4G connectivity to remote regions of Kazakhstan for reliable video calling, conferencing and streaming, and web browsing, with a latency five times lower than on the existing platform based on
geostationary orbit A geostationary orbit, also referred to as a geosynchronous equatorial orbit''Geostationary orbit'' and ''Geosynchronous (equatorial) orbit'' are used somewhat interchangeably in sources. (GEO), is a circular orbit, circular geosynchronous or ...
satellites. On 16 December 2022, the first two (of 13) of SES's next generation
O3b mPOWER O3b mPOWER is a communications satellite system owned and operated by SES. The system uses high-throughput and low- latency satellites in a medium Earth orbit (MEO), along with ground infrastructure and intelligent software, to provide multip ...
(MEO) satellite constellation were successfully launched. O3b mPOWER 3 and 4 were launched on 28 April 2023 and O3b mPOWER 5 and 6 on 12 November 2023, and with six satellites in MEO, the service began commercial operation alongside the existing first generation O3b satellites in April 2024.


Satellites

The satellites are deployed in a circular orbit along the equator at an altitude of (
medium Earth orbit A medium Earth orbit (MEO) is an geocentric orbit, Earth-centered orbit with an altitude above a low Earth orbit (LEO) and below a high Earth orbit (HEO) – between above sea level.
) at a velocity of approximately , each making 5 orbits a day. Due to problems with a component of the first four satellites launched, three of those four have been placed on standby. Each satellite is equipped with twelve fully steerable
Ka-band The Ka band (pronounced as either "kay-ay band" or "ka band") is a portion of the microwave part of the electromagnetic spectrum. The designation "Ka-band" is from Kurz-above, which stems from the German word ''kurz,'' meaning "short". There ...
antennas (two beams for gateways, ten beams for remotes) that use 4.3
GHz The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), often described as being equivalent to one event (or Cycle per second, cycle) per second. The hertz is an SI derived unit whose formal expression in ter ...
of spectrum (2 × 216 MHz per beam) with a proposed throughput of 1.6 
Gbit The bit is the most basic unit of information in computing and digital communication. The name is a portmanteau of binary digit. The bit represents a logical state with one of two possible values. These values are most commonly represented as ...
/s per beam (800 
Mbit/s In telecommunications, data transfer rate is the average number of bits (bitrate), characters or symbols (baudrate), or data blocks per unit time passing through a communication link in a data-transmission system. Common data rate units are multi ...
per direction), resulting in a total capacity of 16 Gbit/s per satellite. Each beam's footprint measures in diameter. O3b claims a mouth-to-ear one-way latency of 179 milliseconds for voice communication, and an end-to-end round-trip latency of 140 ms for data services. The maximum throughput per TCP connection is 2.1 Mbit/s. For maritime applications, O3b claims a round-trip latency of 140 ms, and connectivity speeds of over 500 Mbit/s. The satellites are powered by
gallium arsenide Gallium arsenide (GaAs) is a III-V direct band gap semiconductor with a Zincblende (crystal structure), zinc blende crystal structure. Gallium arsenide is used in the manufacture of devices such as microwave frequency integrated circuits, monoli ...
solar arrays A photovoltaic system, also called a PV system or solar power system, is an electric power system designed to supply usable solar power by means of photovoltaics. It consists of an arrangement of several components, including solar panels to abs ...
and
lithium-ion batteries A lithium-ion or Li-ion battery is a type of rechargeable battery that uses the reversible intercalation of Li+ ions into electronically conducting solids to store energy. Li-ion batteries are characterized by higher specific energy, energy ...
and weigh approximately each. The satellites were constructed by
Thales Alenia Space Thales Alenia Space () is a joint venture between the French technology corporation Thales Group (67%) and Italian defense conglomerate Leonardo (company), Leonardo (33%). The company is headquartered in Cannes, France. It provides space-based ...
, a division of
Thales Group Thales S.A., Trade name, trading as Thales Group (), is a French multinational corporation, multinational aerospace and defence industry, defence corporation specializing in electronics. It designs, develops and manufactures a wide variety of aer ...
. The first satellite (PFM) was built in the
Cannes Mandelieu Space Center The Cannes Mandelieu Space Center is an industrial plant dedicated to spacecraft manufacturing, located in both the towns of Cannes and Mandelieu in France. After a long history in aircraft manufacturing, starting in 1929, the center became incr ...
, while the rest of the constellation was assembled, integrated and tested in Thales Alenia Space Italy's Roman facilities. In September 2017, SES announced
O3b mPOWER O3b mPOWER is a communications satellite system owned and operated by SES. The system uses high-throughput and low- latency satellites in a medium Earth orbit (MEO), along with ground infrastructure and intelligent software, to provide multip ...
, the next generation of O3b satellites and placed an order for an initial seven from
Boeing Satellite Systems The Boeing Satellite Development Center is a major business unit of Boeing Defense, Space & Security. It brought together Boeing satellite operations with that of GM Hughes Electronics' Space and Communications division in El Segundo, Califo ...
using a new satellite platform based on Boeing's 702 line of scalable buses. The
O3b mPOWER O3b mPOWER is a communications satellite system owned and operated by SES. The system uses high-throughput and low- latency satellites in a medium Earth orbit (MEO), along with ground infrastructure and intelligent software, to provide multip ...
constellation of
medium Earth orbit A medium Earth orbit (MEO) is an geocentric orbit, Earth-centered orbit with an altitude above a low Earth orbit (LEO) and below a high Earth orbit (HEO) – between above sea level.
(MEO) satellites for broadband internet services would "be able to deliver anywhere from hundreds of megabits to 10 gigabits to any ship at sea" through 30,000 spot beams, with software-defined routing to direct traffic between the MEO satellites and SES'
geostationary A geostationary orbit, also referred to as a geosynchronous equatorial orbit''Geostationary orbit'' and ''Geosynchronous (equatorial) orbit'' are used somewhat interchangeably in sources. (GEO), is a circular geosynchronous orbit in altitud ...
fleet. The number of O3b mPOWER satellites ordered was increased to 11 and then 13, and on 16 December 2022, the first two
O3b mPOWER O3b mPOWER is a communications satellite system owned and operated by SES. The system uses high-throughput and low- latency satellites in a medium Earth orbit (MEO), along with ground infrastructure and intelligent software, to provide multip ...
satellites were successfully launched, with four more in 2023, and the service began operations alongside the existing O3b constellation in April 2024. The seventh and eighth (upgraded) satellites were launched in December 2024 to increase the constellation's capacity.


List of satellites


Use of medium Earth orbit

O3b MEO is currently the only
high-throughput satellite A high-throughput satellite (HTS) is a communications satellite which provides more throughput than a classic fixed service satellite (FSS). An HTS provides at least twice, though usually 20 times or more, throughput for the same amount of allocat ...
(HTS) system for
internet services An Internet service provider (ISP) is an organization that provides a myriad of services related to accessing, using, managing, or participating in the Internet. ISPs can be organized in various forms, such as commercial, community-owned, non ...
to use the medium Earth orbit; most other existing and proposed systems use satellites in either
geosynchronous orbit A geosynchronous orbit (sometimes abbreviated GSO) is an Earth-centered orbit with an orbital period that matches Earth's rotation on its axis, 23 hours, 56 minutes, and 4 seconds (one sidereal day). The synchronization of rotation and orbital ...
(GEO) or
low Earth orbit A low Earth orbit (LEO) is an geocentric orbit, orbit around Earth with a orbital period, period of 128 minutes or less (making at least 11.25 orbits per day) and an orbital eccentricity, eccentricity less than 0.25. Most of the artificial object ...
(LEO). Although previous satellite internet services primarily used geosynchronous satellites (SES has four geostationary HTS in orbit – Astra 2E,
SES-12 SES-12 is a geostationary communications satellite operated by SES. Satellite description SES-12 was designed and manufactured by Airbus Defence and Space. It has a mass of and has a design life of at least 15 years. Launch SES-12 was su ...
,
SES-14 SES-14 is a geostationary communications satellite operated by SES at 47.5° West, replaces NSS-806, and designed and manufactured by Airbus Defence and Space. The satellite launched on 25 January 2018 at 22:20 UTC along with the Global-scal ...
and
SES-15 SES-15 is a geostationary orbit, geostationary communications satellite operated by SES (company), SES and designed and manufactured by Boeing Satellite Systems. It has a mass of and has a design life of at least 15 years. See also * SES (c ...
), demand for increased bandwidth and for lower latency has shifted the focus for HTS to lower orbits.''Large LEO satellite constellations: Will it be different this time?''
McKinsey & Company, 4 May 2020, Accessed 29 October 2020
The lower the altitude of the orbit, the closer the satellite is to the Earth and the lower the latency and
path loss Path loss, or path attenuation, is the reduction in power density (attenuation) of an electromagnetic wave as it propagates through space. Path loss is a major component in the analysis and design of the link budget of a telecommunication system. ...
es (enabling lower ground station and satellite power, and costs for the same throughput)''LEO constellations and tracking challenges''
Satellite Evolution Group, September 2017, Accessed 30 October 2020
The
propagation delay Propagation delay is the time duration taken for a signal to reach its destination, for example in the electromagnetic field, a wire, speed of sound, gas, fluid or seismic wave, solid body. Physics * An electromagnetic wave travelling through ...
for a round-trip
internet protocol The Internet Protocol (IP) is the network layer communications protocol in the Internet protocol suite for relaying datagrams across network boundaries. Its routing function enables internetworking, and essentially establishes the Internet. IP ...
transmission via a geosynchronous satellite can be over 550 ms, and such latency is the bane of digital connectivity, in particular for automated stock trades, hardcore gaming and
Skype Skype () was a proprietary telecommunications application operated by Skype Technologies, a division of Microsoft, best known for IP-based videotelephony, videoconferencing and voice calls. It also had instant messaging, file transfer, ...
video chats.''Real-Time Latency: Rethinking Remote Networks''
Telesat, February 2020, Accessed 31 October 2020
''LEO and MEO broadband constellations mega source of consternation''
SpaceNews, 13 March 2018, Accessed 29 October 2020
So, many proposed non-geosynchronous satellite internet services have adopted a low Earth orbit of under 2000 km altitude where latency can be as little 40ms, and by 2018 more than 18,000 new LEO satellites had been proposed to launch by 2025. However, a lower orbit also has drawbacks; satellites move faster relative to the ground and can "see" a smaller area of the
Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...
, and so for continuous widespread access require a
constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The first constellati ...
of many satellites, with complex constellation management and tracking by the ground stations. Medium Earth orbit, although higher in altitude than LEO is nevertheless much lower than geosynchronous orbit and so shares many of the advantages of LEO while reducing its drawbacks:''The Gravity of Space Debris''
Via Satellite. March 2019, Accessed 31 October 2020
* Latency as low as 125ms – longer than LEO but substantial improvement over GEO satellites * Longer orbital period than LEO – a smaller constellation needed for continuous "visibility" * Cheaper and simpler telemetry, tracking and control systems than LEO * Higher "look angle" from the ground than LEOs * Longer service life expectancy than LEO satellites * Reduced
Doppler shift The Doppler effect (also Doppler shift) is the change in the frequency of a wave in relation to an observer who is moving relative to the source of the wave. The ''Doppler effect'' is named after the physicist Christian Doppler, who described t ...
problem than LEO * Less orbital overcrowding and space debris than LEO


See also

* SES *
O3b Networks O3b Networks Ltd. was a network communications service provider building and operating a medium Earth orbit (MEO) satellite constellation primarily intended to provide voice and data communications to mobile operators and Internet service prov ...
*
O3b mPOWER O3b mPOWER is a communications satellite system owned and operated by SES. The system uses high-throughput and low- latency satellites in a medium Earth orbit (MEO), along with ground infrastructure and intelligent software, to provide multip ...


References

{{Orbital launches in 2018 Communications satellite constellations Spacecraft launched in 2013 Spacecraft launched in 2014 Spacecraft launched in 2018 First artificial satellites of a country SES (company) Satellites of Luxembourg Spacecraft launched by Soyuz-2 rockets