Speaker Covers Satellite Solution

Jeffery Roberts, Alaska Aerospace Corporation, presented "Using Highly Elliptical Orbits to Provide Satellite Communications to Northern Latitudes" at the chapter's February meeting. Alaska's location in the northern latitudes and dispersed population centers present numerous challenges for conventional communications architectures. Terrestrial-based systems are not feasible because the majority of Alaska towns and villages are not connected by a road system. Geostationary satellites are only within the field of view of the lower half of the state. Low Earth Orbit satellites have low bandwidth and latency problems. However, satellites in highly elliptical orbits (HEOs) present a potential solution for northern latitude communications. Highly elliptical orbits are characterized by a long period of apogee dwell over northern latitudes. There are two major types of HEO orbits: low HEO orbits (approximately 400 km altitude at perigee and 12,000 km at apogee) are close enough to the Earth to provide communications on the move with omni-directional antennas. Two low HEO satellites can provide 24/7 coverage above 55-degree north latitude (latitude of Juneau, Copenhagen, Moscow). Four low HEO satellites can provide 24/7 coverage down to 20 degrees north (Hawaii, Jamaica, Mumbai). Larger HEO orbits, such as Molniya (500 km x 47,000 km) and Tundra (24,500 km x 40,000 km), can provide 24/7 coverage with two or three satellites, yet their higher altitude at apogee will require the use of ground stations with tracking antennas. A combination of low HEO, Molniya and Tundra communications satellites can provide overhead communication solutions for Alaska, other northern locations and even rural areas in the rest of the United States.

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