Sirius 3 is a Swedish geosynchronous communications spacecraft. The spacecraft will provide voice and video communications to Northern Europe and Scandinavia through 15 Ku-band 44 watt transponders after parking at about 5 degrees E longitude.
The satellite is cylindrical in shape, 2.16 m in diameter and 7.76 m in height when deployed. It has two telescoping cylindrical solar panels and antennas that fold for compactness during launch. The Sirius 3 antenna has shaped surface octagonal reflectors, approximately 2 m in diameter, with single offset feeds. This antenna has three surfaces: one for horizontally polarized signals, one for vertically polarized signals, and one for on-station tracking and command.
Sirius 3 carries 15 Ku-band transponders powered by 44 watt traveling-wave tube amplifiers (TWTAs). The spacecraft uses gallium arsenide solar cells to generate a minimum of 1400 watts of spacecraft power at end of life and relies on nickel-hydrogen batteries for power through eclipses. The planned service life is 12 years.
Sirius 3 is used primarily for direct-to-home and cable television services as well as data distribution in Scandinavia and neighboring countries, but is also capable of providing television distribution and high-speed internet data to Greenland. The Ku-band effective isotropic radiated power (EIRP) will be minimum 54 dBW in the primary zone.
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