<div class="htmlview paragraph">Results of thermal mode mathematical evaluation and thermal vacuum tests of the star sensor developed for the “Yamal” project were compared. “TERM” software package was used for mathematical evaluation. The comparison of its results with information, obtained during thermal vacuum tests of sensor in shadow shows the following:</div> <div class="htmlview paragraph"> <ol class="list nostyle"> <li class="list-item"> <span class="li-label">1.</span> <div class="htmlview paragraph">Calculated temperature of unit elements differs from the temperature measured in experiment with the mean square deviation 1.5°C. This deviation does not exceed the mean square error of the model.</div> </li> <li class="list-item"> <span class="li-label">2.</span> <div class="htmlview paragraph">The possibility of objective contamination does exist.</div> </li> <li class="list-item"> <span class="li-label">3.</span> <div class="htmlview paragraph">The star image enlarging does exist due the lens temperature changes.</div> </li> </ol> </div> <div class="htmlview paragraph">The recommendations are proposed to avoid these processes.</div>