Celestri

Last updated

The Celestri Multimedia LEO System was a planned Low Earth orbit (LEO) satellite constellation, which was intended to offer global, low-latency broadband Internet services via Ka-band radio links [1] . It was planned by Motorola circa 1997-1998 as one of the earliest "Internet in the sky" constellations, and as a successor to the company's Iridium satellite constellation, but never built or launched.

The Celestri constellation was envisioned to consist of 63 operational satellites in 7 orbital planes, inclined at 48° with respect to the Equator, plus up to 7 in-orbit spares [1] . Satellites in each plane would follow circular orbits at an altitude of 1400 kilometers [1] . Each satellite was envisioned to contain all hardware and software needed to route traffic throughout the network, including Earth-to-space in the 28.6-29.1 GHz and 29.5-30.0 GHz bands, space-to Earth in the 18.8-19.3 GHz and 19.7-20.2 GHz bands, and space-to-space connections via optical inter-satellite links [1] . Satellites were expected to employ phased array antennas supporting 432 uplink beams and 260 downlink beams per satellite [2] , provided by Raytheon [3] , to communicate with Celestri ground stations, which would have equivalent antenna aperture sizes from 0.3 to 1 meter to support communications at rates from 2.048 to 155.52 Mbps.

Celestri's anticipated cost was $12.9 billion [4] . In May 1998, Motorola announced that it was dropping its plans for the Celestri system, and instead would invest $750 million in the rival Teledesic constellation [5] . The combined project was ultimately abandoned in 2003 [6] .

Related Research Articles

Communications satellite Artificial satellite that relays radio signals

A communications satellite is an artificial satellite that relays and amplifies radio telecommunications signals via a transponder; it creates a communication channel between a source transmitter and a receiver at different locations on Earth. Communications satellites are used for television, telephone, radio, internet, and military applications. There are about 2,000 communications satellites in Earth's orbit, used by both private and government organizations. Many are in geostationary orbit 22,236 miles (35,785 km) above the equator, so that the satellite appears stationary at the same point in the sky, so the satellite dish antennas of ground stations can be aimed permanently at that spot and do not have to move to track it.

Iridium Communications Inc. is a publicly traded American company headquartered in McLean, Virginia. Iridium operates the Iridium satellite constellation, a system of 66 active satellites used for worldwide voice and data communication from hand-held satellite phones and other transceiver units.

Satellite constellation group of artificial satellites working in concert

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 coverage, such that at any time everywhere on Earth at least one satellite is visible. Satellites are typically placed in sets of complementary orbital planes and connect to globally distributed ground stations. They may also use inter-satellite communication.

The Ku band is the portion of the electromagnetic spectrum in the microwave range of frequencies from 12 to 18 gigahertz (GHz). The symbol is short for "K-under", because it is the lower part of the original NATO K band, which was split into three bands because of the presence of the atmospheric water vapor resonance peak at 22.24 GHz, (1.35 cm) which made the center unusable for long range transmission. In radar applications, it ranges from 12 to 18 GHz according to the formal definition of radar frequency band nomenclature in IEEE Standard 521-2002.

Teledesic satellite company

Teledesic was a company founded in the 1990s to build a commercial broadband satellite internet constellation. Using low-Earth-orbiting satellites small antennas could be used to provide uplinks of as much as 100 Mbit/s and downlinks of up to 720 Mbit/s. The original 1994 proposal was extremely ambitious, costing over 9 billion USD and originally planning 840 active satellites with in-orbit spares at an altitude of 700 km. In 1997, the plan was scaled back to 288 active satellites at 1400 km. Teledesic Corporation changed its name to Teledesic, LLC by pro forma assignment of its license, granted on 26 January 1998.

Very-small-aperture terminal

A very-small-aperture terminal (VSAT) is a two-way satellite ground station with a dish antenna that is smaller than 3.8 meters. The majority of VSAT antennas range from 75 cm to 1.2 m. Data rates, in most cases, range from 4 kbit/s up to 16 Mbit/s. VSATs access satellites in geosynchronous orbit or geostationary orbit to relay data from small remote Earth stations (terminals) to other terminals or master Earth station "hubs".

The S band is a designation by the Institute of Electrical and Electronics Engineers (IEEE) for a part of the microwave band of the electromagnetic spectrum covering frequencies from 2 to 4 gigahertz (GHz). Thus it crosses the conventional boundary between the UHF and SHF bands at 3.0 GHz. The S band is used by airport surveillance radar for air traffic control, weather radar, surface ship radar, and some communications satellites, especially those used by NASA to communicate with the Space Shuttle and the International Space Station. The 10 cm radar short-band ranges roughly from 1.55 to 5.2 GHz. The S band also contains the 2.4–2.483 GHz ISM band, widely used for low power unlicensed microwave devices such as cordless phones, wireless headphones (Bluetooth), wireless networking (WiFi), garage door openers, keyless vehicle locks, baby monitors as well as for medical diathermy machines and microwave ovens. India's regional satellite navigation network (IRNSS) broadcasts on 2.483778 to 2.500278 GHz.

Satellite Internet access is Internet access provided through communications satellites. Modern consumer grade satellite Internet service is typically provided to individual users through geostationary satellites that can offer relatively high data speeds, with newer satellites using Ku band to achieve downstream data speeds up to 506 Mbit/s. In addition, new satellite internet constellations are being developed in low-earth orbit to enable low-latency internet access from space.

Telesat, formerly Telesat Canada, is a Canadian satellite communications company founded on May 2, 1969. The company is headquartered in Ottawa.

Inmarsat satellite communications company

Inmarsat is a British satellite telecommunications company, offering global mobile services. It provides telephone and data services to users worldwide, via portable or mobile terminals which communicate with ground stations through thirteen geostationary telecommunications satellites. Inmarsat's network provides communications services to a range of governments, aid agencies, media outlets and businesses with a need to communicate in remote regions or where there is no reliable terrestrial network. The company was listed on the London Stock Exchange until it was acquired by Connect Bidco, a consortium consisting of Apax Partners, Warburg Pincus, the CPP Investment Board and the Ontario Teachers' Pension Plan, in December 2019.

Iridium 33 Communications satellite operated by Iridium Communications

Iridium 33 was a communications satellite launched by Russia for Iridium Communications. It was launched into low Earth orbit from Site 81/23 at the Baikonur Cosmodrome at 01:36 UTC on 14 September 1997, by a Proton-K rocket with a Block DM2 upper stage. The launch was arranged by International Launch Services (ILS). It was operated in Plane 3 of the Iridium satellite constellation, with an ascending node of 230.9°.

Iridium satellite constellation Satellite constellation providing voice and data coverage

The Iridium satellite constellation provides L band voice and data information coverage to satellite phones, pagers and integrated transceivers over the entire Earth surface. Iridium Communications owns and operates the constellation, additionally selling equipment and access to its services. It was conceived by Bary Bertiger, Raymond J. Leopold and Ken Peterson in late 1987 and then developed by Motorola on a fixed-price contract from July 29, 1993, to November 1, 1998, when the system became operational and commercially available.

Iridium 77 communications satellite operated by Iridium Communications.

Iridium 77 is a communications Satellite which is part of a satellite constellation known as Iridium, named after the 77th chemical element of the periodic table, iridium. It was launched in 1998 and as of 2014, operational. It is owned and funded by Iridium, a communications company.

OneWeb satellite constellation Proposed constellation

The OneWeb satellite constellation was a planned initial 650-satellite constellation that was in the process of being completed in 2019–2020, with a goal to provide global satellite Internet broadband services to people everywhere and was previously aiming to provide global services starting in 2021. The constellation was being deployed by OneWeb, formerly known as WorldVu Satellites and headquartered in London, United Kingdom with offices in California, Florida, Virginia, Dubai and Singapore.

X band or SHF Satellite Communication is widely used by military forces for beyond line of sight communications. X band is used because it provides a compromise between the characteristics of different frequency bands which is particularly suited to the needs of military users. The characteristics include interference and rain resilience, terminal size, data rates, remote coverage and whether it is reserved for governmental use.

Starlink Satellite constellation; space-based Internet service

Starlink is a satellite constellation being constructed by SpaceX to provide satellite Internet access. The constellation will consist of thousands of mass-produced small satellites in low Earth orbit (LEO), working in combination with ground transceivers. SpaceX also plans to sell some of the satellites for military, scientific, or exploratory purposes. The SpaceX satellite development facility in Redmond, Washington houses the Starlink research, development, manufacturing, and on-orbit control operations. The total cost of the decade-long project to design, build, and deploy the constellation was estimated by SpaceX in May 2018 to be about US$10 billion.

Raymond J. Leopold is one of the three engineers who in late 1987 conceived of and later designed the Iridium satellite constellation, the first realization of global, wireless, personal communications.

A satellite internet constellation is a constellation of artificial satellites providing satellite internet service. In particular, the term has come to refer to a new generation of very large constellations orbiting in low-Earth orbit (LEO) to provide low-latency, high bandwidth (broadband) internet service.

ACTS Gigabit Satellite Network

The ACTS Gigabit Satellite Network was a pioneering, high-speed communications satellite network in the years 1993-2004, created as a prototype system to explore high-speed networking of digital endpoints.. The system was jointly sponsored by NASA and ARPA, implemented by BBN Technologies and Motorola, and was inducted into the Space Technology Hall of Fame in April 1997.

O3b mPOWER is a communications satellite system currently under construction and due to be launched in 2021. Owned and operated by SES, O3b mPower initially comprises 11 high-throughput and low-latency satellites in a medium Earth orbit (MEO), along with ground infrastructure and intelligent software, to provide multiple terabits of global broadband connectivity for applications including cellular backhaul to remote rural locations and simultaneous international IP trunking.

References

  1. 1 2 3 4 Application for Authority to Construct, Launch and Operate the Celestri Multimedia LEO System, A Global Network of Non-Geostationary Communications Satellites Providing Broadband Services in the Ka Band, filed June 1997 with the Federal Communications Commission, Motorola Global Communications, Inc., Chandler, Arizona.
  2. Satellite Earth Stations and Systems (SES); Broadband satellite multimedia; Part 1: Survey on standardization objectives, ETSI Technical Report TR 101 374-1 V1.2.1 (1998-10), page 50.
  3. "Motorola to Give Raytheon Satellite-Antennae Contract", Wall Street Journal, October 30, 1997.
  4. "Motorola to build $12.9 billion global satellite network Celestri, a direct challenge to Teledesic, SkyBridge", Bloomberg News, June 18, 1997.
  5. "Motorola decides to drop Celestri satellite project, Will invest $750 million in rival Teledesic", Bloomberg News, May 22, 1998.
  6. de Selding, Peter B. "Teledesic Plays Its Last Card, Leaves the Game". Space News, July 14, 2003.