SES Fleet Grows by Two

In August 1999, Hughes Space and Communications International, now Boeing Satellite Development Center, was awarded two satellite contracts from Société Européenne des Satellites (SES) of Luxembourg. The new awards are the 8th and 9th to Hughes from SES, and will bring the total number of satellites in the SES fleet to 13.

Astra 2D, the first spin-stabilized satellite in the SES fleet, is a Boeing 376HP, for high-power, satellite. It was successfully launched on an Ariane 5 on Dec. 19, 2000. The Boeing 376 is one of the most popular spacecraft models. The delivery-in-orbit contract includes the satellite, launch services, and ground station control software for use at the control center, plus training for new satellite controllers. The Astra satellites are controlled from the SES ground station at Betzdorf in Luxembourg.

Stowed (left); In Orbit (right)

Astra 2D is the 55th 376 to be ordered from Hughes and Boeing. It will carry 18 traveling-wave tube amplifiers, 16 of which will be active. The signals will be transmitted via 39-watt traveling-wave tube amplifiers. Astra 2D will deliver digital direct-to-home television to Great Britain and Ireland. Two of the satellite's four on-board receivers will be used at any given time.

The Boeing 376 spin-stabilized spacecraft consists of two main sections. One is the spinning section, which contains the apogee kick motor, power system, primary propulsion, and most of the attitude control and command and telemetry subsystem elements. The fully redundant subsystem controls and monitors the spacecraft through all mission phases. The primary propulsion subsystem controls spacecraft orbital velocity, inclination, attitude, and spin speed. The other main section of the spacecraft is the despun portion, which houses the customized communications payload, including the transmitters, receivers, and antennas. Astra 2D is similar to the other operational Boeing 376HP satellites, the first of which was launched in January 1996. A standard bus will be used.

All Boeing 376 models have two telescoping cylindrical solar panels. These panels and the deployable antennas are stowed for compactness during launch. The highly reliable design makes full use of a nickel-hydrogen battery to maintain uninterrupted broadcasting during eclipses. The Astra 2D solar panels use gallium arsenide solar cells similar to those proven on previous Hughes spacecraft. The 376 design minimizes the number of required mechanisms and has never had a deployment failure.

Boeing Satellite Development Center is the world's leading manufacturer of commercial communications satellites and a major provider of space systems, satellites and payloads for national defense, science and environmental applications.

ASTRA 2D SPECIFICATIONS