High-Power Broadcasting for Europe

Solar wings deployed    1C, 1D    1E, 1F, 1G, 1H, 2A	21 m (68 ft 11 in) 26 m (85 ft 4 in)
Antennas deployed    1C, 1D, 1E, 1F    1G, 1H, 2A	7.4 m (24 ft 3 in) 10 m (32 ft 11 in)
Weight, begining life in orbit    1C, 1D    1E    1F    1G, 1H, 2A	approx 1700 kg (3748 lb) approx 1800 kg (3970 lb) approx 1900 kg (4190 lb) approx 2300 kg (5072 lb)
Width stowed    1C, 1D, 1E, 1F    1G, 1H, 2A	approx 2.7 m x 3.2 m (106 in x 126 in) approx 3.3 m x 3.3 m (130 in x 130 in)
Height stowed    1C, 1D, 1E, 1F    1G, 1H, 2A	4.3 m (14 ft) 5.5 m (17 ft 11 in)

With its constellation of Astra spacecraft, Société Européenne des Satellites (SES) of Luxembourg is delivering analog as well as digital television and radio services across Europe. Hughes Space and Communications Company (HSC), today known as Boeing Satellite Systems, Inc., is building a series of Hughes 601 and Hughes 601HP body-stabilized model spacecraft for SES in its facilities in El Segundo, Calif.

SES ordered its first Hughes 601 satellite, called Astra 1C, in late 1990, after a six-month competitive bidding process. That was followed in late 1991 by an order for a second spacecraft, Astra 1D; in 1992 for Astra 1E; in 1993 for Astra 1F; in 1994 for Astra 1G; in 1995 for 1H; and in 1996 for 2A. In August 1999, SES ordered two new satellites, Astra 2C, a Hughes 601HP, and Astra 2D, a Hughes 376. Astra 1C was successfully launched May 11, 1993, on an Ariane 42L rocket. Astra 1D was launched successfully on an Ariane 42P on Oct. 31, 1994. An Ariane 42L launched Astra 1E on Oct. 18, 1995. Astra 2D is scheduled to launch in 2000, and Astra 2C in 2001.

Astra 1F was the first western satellite launched on a Proton rocket, on April 9, 1996. Astra 1G, also launched on a Proton, was launched Dec. 3, 1997. Astra 2A was launched on a Proton on Aug. 30, 1998. At SES' request, Hughes added a Ka-band payload to Astra 1H to inaugurate interactive media services across Europe. Astra 1H was successfully launched on a Proton rocket on June 18, 1999.

The Hughes' 601 satellite -- now the Boeing 601-- was designed for the higher-power missions of the 1990s. The model was introduced in 1987 to meet anticipated requirements for high-power, multiple-payload satellites for such uses as direct television broadcasting to small antennas, mobile communications, and private business networks.

The Boeing 601 is composed of two modules: the primary structure that carries all launch vehicle loads and contains the propulsion system, bus electronics, and battery packs; and a payload module that holds communications equipment and isothermal heat pipes. Reflectors, antenna feeds, and solar arrays mount directly to the primary structure. Such a modular approach allows work to proceed in parallel on both structures, thereby shortening the manufacturing schedule and test time.

The Astra satellites are similar in appearance to other 601 models, with each having a cube-shaped body and two solar array wings oriented along its north-south axis and the antennas located on the east-west axis.

All the satellites operate in Ku-band and use traveling-wave tube amplifiers (TWTAs) for power. On Astra 1C and 1D, the TWTAs provide 63 watts each; on Astra 1E, it's 85 watts. The power is 82 watts on Astra 1F, 100 watts on Astra 1G and 1H, and 98.5 watts on Astra 2A.

Astra 1C, 1D, and 1E each carry 18 operating transponders and six spares. Astra 1F will operate with 22 transponders for the first five years and 20 transponders (with eight spares) thereafter. Astra 1G, 1H, and 2A will have a minimum of 28 active transponders with 32 being available for the first five years.

The satellites enable SES to provide analog and digital television programs together. Most operate at 19.2 degrees East longitude. On Astra 1C, the 18 transmission frequencies can be selected on-orbit from 34 possibilities. On Astra 1D and 1E, the on-orbit transmission frequency selection is increased to 66 possibilities. On 1F, 1G, 1H, and 2A 56 possibilities are available, most in the BSS band. Because each spacecraft will provide an effective isotropic radiated power (EIRP) typically 51 dBW, these satellites deliver video and audio signals strong enough to be received by existing 60-cm dishes.

Astra 1G is the first in the series with the HS 601HP (for high power) configuration. Astra 2A is identical, but is located at SES' second orbital position of 28.2 degrees East. Enhancements over the basic HS 601 design include the use of gallium arsenide solar cells, instead of silicon, to generate 6 kilowatts of payload power for the Astra spacecraft. Another new feature is an advanced antenna design, using two large lightweight Gregorian reflector systems featuring Hughes' contoured-surface technology.

The 1C and 1D satellites each measure 7.4 meters across with antennas deployed and 21 meters long from the tip of one three-panel solar array wing to the tip of the other. These solar arrays generate a combined 3500 watts of electrical power, backed up by a 28-cell nickel-hydrogen battery for power during eclipse.

The more powerful Astra 1E and 1F have four panels per solar array wing (26 meters tip to tip) to generate 4700 watts and each has a 32-cell nickel-hydrogen battery. Astra 1G and 1H also have four solar panels per wing, with the high-efficiency gallium arsenide solar cells. Astra 1G and 1H use a more powerful battery with 24 large nickel-hydrogen cells.

On the spacecraft, a flight-proven bipropellant propulsion system with an integral 490-Newton (110-lbf) Marquardt liquid apogee motor and 12 thrusters provides the impulse to achieve and maintain the orbit and attitude necessary for geosynchronous operation.

Astra 2A is using Hughes' xenon ion propulsion system (XIPS) for north/south stationkeeping. This technology provides a significant reduction in launch mass while maintaining the 15-year service life. Astra 2C will also use XIPS.

SES, founded in 1985, is a privately owned satellite system operator. Television channels are uplinked from several cities in Europe and signals are broadcast back by the satellite to individual homes, blocks of apartments, and cable networks. The Astra satellites are controlled from the SES ground station at Betzdorf in Luxembourg.

Public Relations
Boeing
P.O. Box 92919 (S10/S323)
Los Angeles, CA 90009
USA
(310) 364-6363
www.boeing.com/satellite