Space Segment
Thuraya’s space segment consists of satellites in the space and satellite’s control facility on the ground.
Thuraya has two body-stabilized geostationary satellites equipped with high power multiple spot beam mobile payload. One satellite is already launched in orbit (t he Thuraya-1 satellite was successfully launched on board a Sea Launch Zenit-3SL rocket from the equator in the middle of the Pacific Ocean on 21st October 2000) and the other satellite is a ground-based spare. The second satellite will be launched after two or three years of Thuraya’s commercial service launch to meet more traffic demand.
- the first satellite is forecast to have the capacity to handle 1.75 million subscribers.
- the second satellite will be able to add another 40% capacity.
- the first satellite is located at 44° East.
- the second satellite has a slot earmarked at 54° or 28° East.
Thuraya satellite comprises the bus and the payload. The bus is the on-board equipment pointing the spacecraft to the earth, maintaining the satellite attitude, and securing the power and thermal control to the spacecraft. The payload is the communication equipment including the on-board antennas, the digital signal processor and the satellite traffic switch.
The satellite is transmitting and receiving calls through a single 40-foot aperture antenna and using 250-300 spot beams to provide mobile telephone services that are compatible with GSM. Onboard digital signal processing will route the calls directly from one handheld unit to another, or to the terrestrial network. The satellite system provides up to 13,750 simultaneous duplex channels to support the following communication links: gateway-to-mobile link, mobile-to-gateway link, and mobile-to-mobile link.
The system provides the flexibility to accommodate changes in Thuraya’s traffic by means of a re-programmable payload in the satellite. This supports modifications to the satellite’s coverage area and optimisation of performance over geographical areas where high traffic demand exists. The processor creates a large number of spot beams that can be redirected, wherever this is needed, even after the satellite is placed in orbit: from big cities or rural areas to ships at sea.
The satellite ground control equipment is split into three categories, the command and monitoring equipment, the communication equipment, and the orbital analysis and determination equipment.
The orbital analysis and determination equipment is responsible for calculation of the satellite orbit around the earth in the space and the required housekeeping maneuver that is to be implemented on the spacecraft in order to maintain the spacecraft in the same velocity as the earth rotation.
The command and monitoring equipment are responsible of monitoring the spacecraft health and commanding the spacecraft to the desired attitude as well as performing the station-keeping maneuver designed by the orbital operations. The command and monitoring equipment are categorized to Satellite Operation Center ( SOC) and Satellite Payload Control Point (SPCP). The SOC is responsible for controlling and monitoring the spacecraft structure and health while the SPCP is responsible for controlling and monitoring the satellite payload.
The communication equipment is used to transmit the commands and receive the spacecraft status and traffic over an amenable link .