Estimation of the Center of Simulated Planetary Bodies1

The task of centering the simulated image of a planetary body on a display representing the viewscreen of a satellite was investigated in a study employing both male and female subjects. It was found that task performance, as measured by relative radial error, is significantly poorer for crescent and gibbous bodies than for full-phase bodies, and that a circular screen is significantly better than a rectangular one. No significant difference appears for the three diameters of planetary image which were tested. There occur large differences among individuals within the subject group, and the male group exhibits lower error scores than the female. The best subject performed at a level of approximately 1 per cent estimation for all conditions. This amount of operator error is theoretically compatible with the requirements for attitude control during the re-entry of a satellite vehicle.