"Big LEO" Constellation Architecture Competitive Analysis : A Systems Oriented Approach
- Paper ID
IAF-97-M.4.05
- author
- company
Efficient Frontier Astronautics, Inc.
- country
U.S.A.
- year
1997
- abstract
Perhaps the most exciting post-Cold War development in the aerospace industry is the advent of commercial multi-satellite constellation projects. In both breadth and depth, these constellation ventures present enormous technical challenges and tremendous financing hurdles before becoming a reality, much less a commercial success. The nongeostationary orbit mobile satellite service (NGSO MSS) constellations, often referred to as “Big LEOs”, represent over US$20 billion in equity, bond and debt investments. Although each venture employs very different technical approaches, each one claims to be the superior technical solution. The following study- analyzes the competitiveness of the constellation orbital architectures chosen by the three leading Big LEO contenders: Iridium, Globalstar and ICO. While astrodynamicists typically focus on achieving continuous near-global coverage via the least number of spacecraft, a systems-oriented approach would include other pertinent design parameters. Given a mask angle (ground elevation angle) constraint, the coverage achieved by a given orbit selection and constellation configuration denotes simple satellite visibility from the Earth’s surface. However true availability, the ability to robustly provide revenue generating caller-minutes with a high quality of service, further requires consideration of such factors as: » Signal strength - building penetration, urban “canyons” * Geolocation issues - latitude distribution of the addressable market ® Market characteristics - call duration and distance statistics These issues should directly affect the constellation configuration decisions of orbit selection, number of orbital planes, satellites per plane, and phasing strategy. Conversely, the success with which a constellation configuration is effective at accommodating these design challenges is a good benchmark of the competitiveness and relative viability of the Big LEOs.