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Aviation History
1994
1994 - 0034.PDF
COMMUNICATIONS SATELLITES Final licensing approval for the Orhcomm global- communications-satellite system is expected to he approved in early 1994. Tim Furniss reviews the project. SPACE MESSENGERS V: ^ital communications abso lutely any place on Earth." That is the official trading slogan for the Orbcomm satellite system, for which Orbital Sci ence's subsidiary company, Orbital Com munications (OCC), of Dulles, Virginia, is expected to receive final licensing ap proval early this year from the US Federal Communications Commission (FCC). The Orbcomm system is designed to provide "virtual full-time, affordable, two- way message communications to users worldwide through a constellation of 26 or more small satellites", says OCC. The first two satellites will be launched into 785km, circular, 45°-inclination orbits in 1994, with the remaining 24 being launched in 1995. A further eight may be launched later to improve service to equatorial regions. The launch vehicles will be Orbital Sciences' Pegasus XL air- launched solid-propellant boosters, which will carry eight Orbcomms at a time. OCC has signed an agreement with Teleglobe of Canada for the joint financ ing and operation of the Orbcomm sys tem. The two-phase agreements will provide the estimated $135 million cost for the construction, launch and opera tion of the satellites and related ground equipment and software. A public offering of 2.8 million shares of common stock in Orbital Sciences is expected to provide up to $20 million for further Orbcomm development. Up to five years ahead of other pro posed worldwide voice-communications systems, such as the Inmarsat P and the Iridium, Orbcomm customers will be able to send and receive short, but vital, messages for only a "few cents each", says OCC. Orbcomm pocket-sized personal communicators are expected to cost be tween $50 and $400. Applications include two-way messag ing, emergency rescue in remote location, fleet-management automotive communi cations, remote industrial-asset monitor ing, stolen-vehicle recovery and two-way electronic-mail communications. OCC has an agreement with Trimble Navigation of, California, for the technical development and marketing of products and services which combine the capabili ties of Orbcomm and Trimble's global- positioning system (GPS) technology. The companies will define and develop advanced applications of Orbcomm's cap ability for the transmission of GPS- derived navigation and position informa tion. Specially designed units will be developed to service both applications. "Pairing capabilities will allow real-time global hand-held communications of highly accurate GPS information at low cost," says Alan Parker, OCC's president. The customer base will be increased to include military personnel and surveyors. There are 400,000 customers for GPS in the USA alone. ORBCOMM BOOST The FCC boosted Orbcomm in October 1993, when it adopted the system's "re- zoned" worldwide spectrum allocations, providing the basis for final licensing. "The FCC recognised Orbcomm's ad vanced technologies", says Parker. "We believe that this is the first time that uniform worldwide spectrum allocations and regulations have been established in such a short time, reflecting the intense interest in the new services," he adds. The Orbcomm satellite is based on Orbital Sciences' MicroStar standard small-satellite platform. The 39kg space craft incorporates several innovations in component miniaturisation and light weight materials. The round, thin satellite is 1.04m in diameter and 0.16m deep when stowed like a disc for launch. Each is ejected one-by-one by means of springs from the booster's third stage. Its two rigid, articulated solar- cell arrays, which open like lids from the disc, are the thinnest ever built, but generate 0.23kW of power. The satellite — with a wingspan of 2.25m when deployed — incorporates 17 data processors and seven antennae, in cluding the 2.64m-long VHF/UHF an tenna. The 26-satellite system will be able to transmit and receive about 50,000 messages every hour, or over 5 million messages a day worldwide. The MicroStar bus also serves as the basis for Orbital Sciences' MicroLab space- experiments service, which was selected by NASA as a $7 million, low-cost science platform for atmospheric research and GPS-related meteorological experiments. In February 1993, a piggyback space craft was launched from a Pegasus booster to provide important frequency informa tion to Orbcomm network engineers. The Orbcomm Capabilities Demonstration Sat ellite (CDS) provided data for assisting in writing and testing network-control- centre software, which has already simu lated a throughput ol over 1 million messages an hour. Two-way data messages have also been transmitted between the CDS and proto type hand-held mobile communicators in the USA. The ground-breaking ceremony for the first gateway Earth Station in New York state was made in August 1993, while three more will be built in Georgia, Arizona and Washington state. "Orbcomm will revolutionise the way we think about and use personal communications,". says David Thompson, Orbital Sciences' presi dent and chief executive. o An artist's impression of the Orbcomm communications system 32 FLIGHT INTERNATIONAL 5-11 January, 1994
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