An artist's concept of ICO satellite. Photo: Boeing

Boeing Satellite Systems, Inc. (BSS), will build 15 communications satellites for London-based New ICO, formerly ICO Global Communications. The satellites will be used in a global satellite-based mobile communications system that will offer digital data and voice services as well as the satellite equivalent of third-generation (3G) wireless services, including wireless Internet and other packet-data services.

New ICO acquired the assets of ICO Global Communications (Holdings) Limited, which was established in January 1995 to provide global mobile personal communications services by satellite. The business was renamed New ICO following the successful $1.2 billion acquisition of the former ICO group. The acquisition was led by telecommunications pioneer Craig McCaw and completed in May 2000.

ICO ordered its first 12 satellites in July 1995, and three more in September 2000. All are versions of the popular Boeing 601 model, with selected subsystems modified for the special requirements of medium-Earth orbit. The first ICO satellite was destroyed in an unsuccessful launch March 12, 2000, on a Sea Launch vehicle from a platform in the Pacific Ocean.

The original 12 satellites were designed primarily for global mobile voice telephony services. Plans were announced in 2000 for BSS to modify the 11 remaining original spacecraft currently in production for the revamped New ICO system. The spacecraft modifications will assist in the enhancement of the New ICO constellation to provide high-quality voice and packet-data services. New ICO expects to begin service in 2003.

Under a separate contract, BSS is a strategic partner in ICO, with an original investment of $93.8 million. Other investors include many of the world's leading telecommunications operators, together currently servicing more than 10 million customers.

Boeing technicians prepare the ICO satellite prior to shipment to Cape Canaveral for launch aboard the Atlas 2AS rocket. Photo: Boeing

The New ICO satellite design is one of the most complex ever undertaken by BSS and incorporates a number of unique design features. The satellites carry more computing power than 600 Pentium III-based computers; feature innovative transmit and receive antennas allowing direct air link to users; and use a so-called "smart processor" that is capable of adapting beam configuration to match usage and make the most efficient use of the bandwidth available. These features give New ICO unprecedented flexibility to meet ever-changing market demands on a global basis.

Upon full deployment, ICO users will have the choice of two planned handheld products: a compact dual-mode handset compatible with the ICO network and standard GSM protocol, and a cradle accessory that customers can use to adapt a standard cellular phone for satellite communication. The dual-mode handsets will select either satellite or terrestrial modes of operation automatically or under user control, subject to the availability of the satellite and terrestrial systems and the user's service arrangement.

The ICO satellite constellation will consist of 10 active satellites operating for 12 years in two orthogonal planes of medium-Earth orbit at an altitude of 10,390 kilometers (6,456 miles). The orbits will be inclined at 45 degrees to the equator with each plane having five operational satellites plus one spare.

The orbital pattern is designed for significant coverage overlap, ensuring that usually two - but sometimes three or four - satellites will be in view of a user and a satellite access node (SAN) at any time. Each satellite will cover approximately 25 percent of the Earth's surface at a given time.

The satellites will communicate with terrestrial networks through the ICONET, a high-bandwidth global Internet Protocol (IP) network. This will consist of 12 Earth stations or SANs located around the globe, connected via high-speed links. Eleven of the SANs have been constructed.

The satellite orbits have been selected to provide continuous coverage of the entire globe while allowing users to benefit from high elevation angles averaging over 40 degrees. An instantaneous view of the coverage provided by 10 satellites at an elevation of 0 degrees or more is shown in the accompanying diagram.

Illustration of ICO satellite coverage zones. Photo: Boeing

Each satellite will carry an integrated C- and S-band payload - with a total of 5,100 watts of power and a peak effective isotropic radiated power of 58 dBW - to support 4,500 simultaneous telephone calls. An onboard narrow band digital processor will perform channelization, routing and beamforming of the S-band payload.

The digital processor can route communications to mobile users anywhere in 163 S-band spot beams over 30 MHz of bandwidth, depending on changing traffic demand. The 163 spot beams are realized by separate transmit and receive active direct radiating arrays (DRA). Each antenna has 127 radiating elements and associated bandpass filtering and amplification.

Each ICO satellite will have a pair of four-panel solar wings, with dual-junction gallium arsenide solar cells shielded with 30 mils of cover glass. The solar arrays will provide 8,900 watts of end-of-life power.

The ICO satellites will use Sun nadir steering to maintain the solar array and antenna array pointing. Sun nadir steering entails keeping a satellite's solar array pointed toward the Sun while keeping its S-band DRA antenna pointed toward the Earth. Depending on the time of year, the spacecraft will perform a yaw turn that is centered at local spacecraft noon and midnight to optimize thermal and solar performance.

Direct placement of the satellites into orbit by the launch vehicle allows for the simplification of the standard Boeing 601 propulsion system.