SEMI-FLEXIBLE PHOTOVOLTAIC SOLAR ARRAY

RECENT EFFORTS TO REDUCE THE MASS OF SOLAR ARRAY COMPONENTS HAVE CONCENTRATED ON TWO MAIN THEMES: IMPROVING SOLAR CELL EFFICIENCY, THEREBY REDUCING ARRAY AREA AND USING LIGHTER WEIGHT ARRAY SUBSTRATE MATERIALS. WITH THE CURRENT INTEREST IN LIGHTSATS FOR VARIOUS APPLICATIONS, A LOW MASS ARRAY SYSTEM IS DESIRABLE FOR SMALL POWER REQUIREMENTS. AT PRESENT, HIGH-EFFICIENCY SOLAR CELLS ARE TOO COSTLY FOR MANY MISSIONS. THE LIGHTWEIGHT ARRAY DESIGNS HAVE CONSISTED OF "FLEXIBLE" SUBSTRATES IN EITHER ROLLED (FRUSA AND HUBBLE ST), AND FLATPACK FOLD-OUT (SAFE AND APSA) CONFIGURATIONS. THE PRIMARY LIMITATIONS OF THESE DESIGNS FOR LOW-POWER APPLICATIONS IS THAT A LARGE STORAGE HOUSING AND DEPLOYMENT MECHANISM ARE REQUIRED. THESE LIMITATIONS MEAN THAT THESE ARRAY ARE ONLY LIGHTWEIGHT FOR HIGH POWER APPLICATIONS, >5KW. FOR SMALLER ARRAYS, THE LOWER MASS OF THE SUBSTRATE IS OVERWHELMED BY THE MECHANICAL HARDWARE'S MASS, WHICH IS GENERALLY NOT AS SCALABLE TO POWER AS THE BLANKET AREA. ALSO, BECAUSE OF STIFFENING RODS USED FOR LATERAL SUPPORT, QUICK RETRACTION IS VIRTUALLY IMPOSSIBLE, WHICH COULD HAVE SURVIVABILITY IMPLICATIONS. A MORE TRADITIONAL RIGID ARRAY IS FOLDED AND SELF-SUPPORTING FOR STORAGE, EASILY UNFOLDED, AND QUICKLY RETRACTED IF NECESSARY. UNFORTUNATELY, THE PANELS USED IN THESE DESIGNS HAVE SUBSTANTIAL MASS. A COMPROMISE BETWEEN THESE CONCEPTS, A SEMI-FLEXIBLE SOLAR ARRAY, WOULD PROVIDE A LIGHTER ARRAY FOR SMALLER SPACECRAFT. SUCCESSFUL COMPLETION OF THIS EFFORT WILL SUPPORT NUMEROUS GOVERNMENT LIGHTSAT PROGRAMS, INCLUDING BRILLIANT PEBBLES, TACSAT, AND NASA'S EARTH OBSERVING SYSTEM (EOS). FURTHERMORE, BECAUSE OF THE PLANNED RETRACTIBILITY OF THE SEMI-FLEXIBLE SOLAR ARRAY, THERE IS AN INHERENT SYSTEM SURVIVABILITY THAT COULD BE ENHANCED WITH THE ADDITION OF A SIMPLE OUTBOARD HEATSHIELD.