ENGINEERING

Survival of the Fittest Satellites

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Science  02 Nov 2001:
Vol. 294, Issue 5544, pp. 961
DOI: 10.1126/science.294.5544.961a

Constellations of satellites support communication worldwide and collect observations of Earth for commercial, military, and scientific purposes. Low-altitude satellites offer faster communication and reduced operating costs; unfortunately, the lower the altitude, the greater the problem of Earth's curvature, creating longer times during which the satellites are out of contact with ground stations.

To tackle this problem, Williams et al. have developed a genetic algorithm to determine the optimum spacing and orbital parameters for a constellation in order to maximize communications. A random set of initial designs was generated, and the best designs were allowed to interact and produce new designs (offspring). Their algorithm avoids local minima and can sample areas of design space that might not be considered otherwise. Surprisingly, the authors find that for three satellites, an optimum design would require asymmetric spacing, such that two satellites would be close together and far from the third—not a design that engineers would select intuitively.—LR

J. Astronaut. Sci., in press.

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