Galaxy 11 is an American geostationary

communications satellite A communications satellite is an artificial satellite that relays and amplifies radio telecommunication signals via a transponder; it creates a communication channel between a source transmitter and a receiver at different locations on Earth. C ...

which is operated by

Intelsat Intelsat S.A. (formerly INTEL-SAT, INTELSAT, Intelsat) is a multinational satellite services provider with corporate headquarters in Luxembourg and administrative headquarters in Tysons Corner, Virginia, United States. Originally formed as In ...

. It is located in

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 geosynchronous orbit in altitud ...

at a

longitude Longitude (, ) is a geographic coordinate that specifies the east–west position of a point on the surface of the Earth, or another celestial body. It is an angular measurement, usually expressed in degrees and denoted by the Greek letter l ...

of 32.8 degrees east, where it serves as a backup to the

Intelsat 802 Intelsat 802 was a communications satellite operated by Intelsat. Launched in 1997 it was operated in geostationary orbit at a longitude of 174 degrees west for around fourteen years. Satellite The second of six Intelsat VIII satellites to be ...

spacecraft. It was originally operated at 99° West and later spent most of its operational life at 91° West, from where it was used to provide communications services to

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

and

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

. Galaxy 11 was built for

PanAmSat The former PanAmSat Corporation founded in 1984 by Reynold (Rene) Anselmo, was a satellite service provider headquartered in Greenwich, Connecticut, United States. It operated a fleet of communications satellites used by the entertainment ind ...

Hughes Space and Communications The Hughes Aircraft Company was a major American aerospace and defense contractor founded on February 14, 1934 by Howard Hughes in Glendale, California, as a division of Hughes Tool Company. The company was known for producing, among other prod ...

, and is based on the HS-702

satellite bus A satellite bus (or spacecraft bus) is the main body and structural component of a satellite or spacecraft, in which the payload and all scientific instruments are held. Bus-derived satellites are opposed to specially produced satellites. Bus-d ...

. It was the first HS-702 to be launched, and the first satellite to be equipped with an

XIPS The gridded ion thruster is a common design for ion thrusters, a highly efficient low-thrust spacecraft propulsion method running on electrical power by using high-voltage grid electrodes to accelerate ions with electrostatic forces. History Th ...

propulsion system. It carries 24 G/H band and 40 J band (IEEE C and s respectively)

transponder In telecommunications, a transponder is a device that, upon receiving a signal, emits a different signal in response. The term is a blend word, blend of ''transmitter'' and ''responder''. In air navigation or radio frequency identification, a T ...

s, and at launch it had a mass of , with an expected operational lifespan of around 15 years. As the first HS-702 to fly, Galaxy 11 was one of the six which were launched before a design flaw in the type's solar arrays was discovered.

Solar concentrator Concentrated solar power (CSP, also known as concentrating solar power, concentrated solar thermal) systems generate solar power by using mirrors or lenses to concentrate a large area of sunlight into a receiver. Electricity is generated when ...

s, used to increase the amount of sunlight falling on the arrays, were fogging up due to vapours emitted by the satellite. This reduces the output of the solar arrays, and is expected to result in a reduced operational lifespan. Following the discovery of the fault,

US$ The United States dollar (symbol: $; code: USD; also abbreviated US$ or U.S. Dollar, to distinguish it from other dollar-denominated currencies; referred to as the dollar, U.S. dollar, American dollar, or colloquially buck) is the official ...

130 million insurance was claimed on the satellite. The satellite was transferred to Intelsat when it merged with PanAmSat in 2006. The launch of Galaxy 11 was conducted by

Arianespace Arianespace SA is a French company founded in 1980 as the world's first commercial launch service provider. It undertakes the operation and marketing of the Ariane programme. The company offers a number of different launch vehicles: the heavy ...

, using an

Ariane 44L The Ariane 4 was a European expendable space launch system, developed by the '' Centre national d'études spatiales'' (CNES), the French space agency, for the European Space Agency (ESA). It was manufactured by ArianeGroup and marketed by Ari ...

carrier rocket flying from

ELA-2 ELA-2, short for Ensemble de Lancement Ariane 2 (French for Ariane Launch Area 2), was a launch pad at the Centre Spatial Guyanais in French Guiana. It was used by Arianespace for two Ariane 3 launches (V17 in 1986, V25 in 1988), the second Ariane ...

at the

Guiana Space Centre The Guiana Space Centre (french: links=no, Centre spatial guyanais; CSG), also called Europe's Spaceport, is a European spaceport to the northwest of Kourou in French Guiana, a region of France in South America. Kourou is located approximatel ...

. The launch occurred at 00:50 UTC on 22 December 1999. It successfully placed Galaxy 11 into a

geosynchronous transfer orbit A geosynchronous transfer orbit or geostationary transfer orbit (GTO) is a type of geocentric orbit. Satellites that are destined for geosynchronous (GSO) or geostationary orbit (GEO) are (almost) always put into a GTO as an intermediate step f ...

, from which it raised itself to geostationary orbit by means of an onboard

R-4D The R-4D is a small hypergolic rocket engine, originally designed by Marquardt Corporation for use as a reaction control system thruster on vehicles of the Apollo crewed Moon landing program. Today, Aerojet Rocketdyne manufactures and markets m ...

apogee motor. Its insertion into geosynchronous orbit occurred at 16:30 on 2 January 2000. The satellite was originally scheduled to be launched by

Sea Launch Sea Launch was a multinational—Norway, Russia, Ukraine, United States—spacecraft launch company founded in 1995 that provided orbital launch services from 1999–2014. The company used a mobile maritime launch platform for equatorial lau ...

, on the maiden flight of the

Zenit-3SL The Zenit-3SL is an expendable carrier rocket operated by Sea Launch. First flown in 1999, it has been launched 36 times, with three failures and one partial failure. It is a member of the Zenit family of rockets, and is built by the Yuzhnoye Des ...

, however the contract was transferred to Arianespace, and Sea Launch replaced Galaxy 11 with a

DemoSat A DemoSat is a boilerplate spacecraft used to test a carrier rocket without risking a real satellite on the launch. They are most commonly flown on the maiden flights of rockets, but have also been flown on return-to-flight missions after launch ...

for their maiden flight. It currently operates at 44.9° East. On 10 September 2022, the

International Scientific Optical Network The International Scientific Optical Network or ISON (russian: Международная научная оптическая сеть, Пулковская кооперация оптических наблюдателей) is an international p ...

coordinated by the

Keldysh Institute of Applied Mathematics The Keldysh Institute of Applied Mathematics (russian: Институт прикладной математики им. М.В.Келдыша) is a research institute specializing in computational mathematics. It was established to solve computati ...

reported that Galaxy 11 had been partially destroyed in geostationary orbit, which is potentially dangerous for other satellites. Despite the report from the Keldysh Institute of Applied Mathematics, the Galaxy 11 satellite continues to operate nominally with no disruption to communications service.

References

{{Orbital launches in 1999 Spacecraft launched in 1999 Communications satellites in geostationary orbit

See also

References