TIMING SCHEDULE OPTIMIZATION FOR EARTH ORBIT
MASSACHUSETTS INST OF TECH CAMBRIDGE
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The location times of thirty measurement points for a spacecraft in a circular, planar earth orbit are varied to minimize a cost function, the sum of the squared components of position uncertainty, at a pre-determined target. In addition, the optimum schedule of horizon references for the star-elevation measurement to be used at each point is determined with respect to the same cost function. A steepest-descent computer program was written to perform the optimization in each case. It is shown that the measurement times collect into four clusters from a nominal schedule in which they are equally spaced. A cost reduction greater than 80 is realized. The horizon-selection procedure defines certain areas along the trajectory where one or the other horizon is preferred. When carried out simultaneously with a time optimization, this procedure results in only a slight improvement over the case where a single horizon is used for each measurement.
- Celestial Mechanics