THE PRIMARY OBJECTIVE OF THE PROJECT IS TO DESIGN, BUILD AND TEST A HELIOSTAT WITH A REFLECTOR WHOSE SHAPE IS AUTOMATICALLY ALTERED THROUGHOUT THE DAY. OPTICAL PRINCIPLES TELL US THAT IF THE CONCENTRATION OF ENERGY AND TEMPERATURE AT A TOWER-MOUNTED RECEIVER ARE TO BE MAXIMIZED, THE IDEAL REFLECTOR SHAPE IS THAT WHICH FOCUSES AN IMAGE OF THE SUN’S DISC ON THE RECEIVER. BUT THIS IDEAL SHAPE CHANGES THROUGHOUT THE DAY, AS THE SUN MOVES THROUGH THE SKY AND THE ANGLE AT WHICH SUNLIGHT STRIKES THE REFLECTOR CHANGES. OUR OBJECTIVE IS TO DEMONSTRATE A HELIOSTAT THAT REALIZES THE IDEAL CHANGING CONCAVE TOROID SHAPES IN THE MECHANICALLY SIMPLEST AND LEAST EXPENSIVE WAY, USING COMPONENTS THAT CAN BE MASS PRODUCED AT LOW COST. THE FOCUSING AND IMAGING PERFORMANCE OF THE PROTOTYPE WILL BE MEASURED, AND THE POTENTIAL FOR ANNUAL IMPROVEMENT OVER CONVENTIONAL HELIOSTATS WITH FIXED, CANTED MIRROR SEGMENTS WILL BE EVALUATED BY MODELING THE PERFORMANCE OF A FIELD OF THESE HELIOSTATS.