Galaxy IV
Encyclopedia
Galaxy IV was a model HS-601 satellite built by Hughes Space and Communications Company (HSC). The satellite, which carried a payload of both C band
and Ku band
transponder
s, was launched on June 24, 1993 and operated by PanAmSat
Corporation.
Control of Galaxy IV was lost on May 19, 1998 when the satellite's primary control processor failed. The backup control processor had suffered a previously undetected anomaly, and PanAmSat was not able to regain control of the spacecraft. Galaxy IV was declared a loss on May 20, 1998. Failure of the primary control processor was attributed to tin whisker
growth, a phenomenon in which tendrils grow from solder, causing an electrical short circuit. Engineers believe that a hole developed in the conformal wax coating over the solder, allowing whiskers to develop.
The loss of this satellite was very disruptive to telecommunications in the United States
. Pager
s were affected greatly; service was not restored for days. Wire news services, like Reuters
, were also affected. The TV network CBS
had to use alternate means of transmitting its programs, as did NPR.
At the time of failure, Galaxy IV was in geostationary orbit
at 99°W. This orbital slot was briefly occupied by Galaxy 4R
, and is now occupied by the Galaxy VI satellite. Galaxy IV remains in space.
C band
The C band is a name given to certain portions of the electromagnetic spectrum, including wavelengths of microwaves that are used for long-distance radio telecommunications. The IEEE C-band - and its slight variations - contains frequency ranges that are used for many satellite communications...
and Ku band
Ku band
The Kμ band is a portion of the electromagnetic spectrum in the microwave range of frequencies. This symbol refers to —in other words, the band directly below the K-band...
transponder
Transponder
In telecommunication, the term transponder has the following meanings:...
s, was launched on June 24, 1993 and operated by PanAmSat
PanAmSat
The former PanAmSat Corporation founded in 1984 by Reynold Anselmo, was a satellite service provider headquartered in Greenwich, Connecticut. It operated a fleet of communications satellites used by the entertainment industry, news agencies, internet service providers, government agencies, and...
Corporation.
Control of Galaxy IV was lost on May 19, 1998 when the satellite's primary control processor failed. The backup control processor had suffered a previously undetected anomaly, and PanAmSat was not able to regain control of the spacecraft. Galaxy IV was declared a loss on May 20, 1998. Failure of the primary control processor was attributed to tin whisker
Whisker (metallurgy)
Metal whiskering is a crystalline metallurgical phenomenon involving the spontaneous growth of tiny, filiform hairs from a metallic surface. The effect is primarily seen on elemental metals but also occurs with alloys....
growth, a phenomenon in which tendrils grow from solder, causing an electrical short circuit. Engineers believe that a hole developed in the conformal wax coating over the solder, allowing whiskers to develop.
The loss of this satellite was very disruptive to telecommunications in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
. Pager
Pager
A pager is a simple personal telecommunications device for short messages. A one-way numeric pager can only receive a message consisting of a few digits, typically a phone number that the user is then requested to call...
s were affected greatly; service was not restored for days. Wire news services, like Reuters
Reuters
Reuters is a news agency headquartered in New York City. Until 2008 the Reuters news agency formed part of a British independent company, Reuters Group plc, which was also a provider of financial market data...
, were also affected. The TV network CBS
CBS
CBS Broadcasting Inc. is a major US commercial broadcasting television network, which started as a radio network. The name is derived from the initials of the network's former name, Columbia Broadcasting System. The network is sometimes referred to as the "Eye Network" in reference to the shape of...
had to use alternate means of transmitting its programs, as did NPR.
At the time of failure, Galaxy IV was in geostationary orbit
Geostationary orbit
A geostationary orbit is a geosynchronous orbit directly above the Earth's equator , with a period equal to the Earth's rotational period and an orbital eccentricity of approximately zero. An object in a geostationary orbit appears motionless, at a fixed position in the sky, to ground observers...
at 99°W. This orbital slot was briefly occupied by Galaxy 4R
Galaxy 4R
Galaxy 4R is a Panamsat-owned communications satellite previously at an orbital location of 99° W, a slot once occupied by the Galaxy IV, which suffered a failure in 1998. G4R was launched on April 18, 2000, with an Ariane launch vehicle, and covered North America with twenty-four transponders...
, and is now occupied by the Galaxy VI satellite. Galaxy IV remains in space.