FOR A SPACECRAFT TO BE MISSION READY IT MUST BE ABLE TO REGULATE ITS OWN TEMPERATURE. NECESSARY SYSTEM ELECTRONICS SENSITIVE SCIENTIFIC INSTRUMENTS AND ESPECIALLY ASTRONAUTS ONBOARD THE SPACECRAFT MUST OPERATE WITHIN A SPECIFIC TEMPERATURE WINDOW OR THE MISSION WILL FAIL. HOWEVER THE TENDENCY OF A SPACECRAFT'S TEMPERATURE IS TO INCREASE. THE SUN AND THE EARTH RADIATE HEAT THAT IS ABSORBED INTO THESPACECRAFT WHILE ON BOARD ELECTRONICS AND PERSONNEL GENERATE HEAT INSIDE THE SPACECRAFT. ON EARTH THIS EXCESS HEAT WOULD NORMALLY BE REMOVED BY AIR AROUND THE SPACECRAFT. HOWEVER THE SPACECRAFT IS IN THE VACUUM OF SPACE. AS SUCH THE HEAT MUST ULTIMATELY BE EMITTED AWAY FROM THE SPACECRAFT AS RADIATION. COMPONENTS DESIGNED TO EMIT THIS EXCESS HEAT ARE CALLED RADIATORS AND ARE A VITAL PART OF THE THERMAL MANAGEMENT SYSTEM OF ANY SPACECRAFT. HOWEVER BECAUSE THE HEAT LOAD ON A SYSTEM VARIES WITH ORBIT RADIATORS ARE DESIGNED FOR A WORST CASE HEATING SCENARIO. AS SUCH ANY HEATING CONFIGURATION OUTSIDE OF THE DESIGNED HEATING SCENARIO CAUSES THE RADIATOR TO BEHAVE IN AN UNDESIRABLE WAY EMITTING MORE HEAT THAN DESIRED OR ABSORBING TOO MUCH HEAT FROM THE SURROUNDINGS. LIKEWISE THESE RADIATORS ARE HEAVY OFTEN COMPRISING 30 - 40 PERCENT OF TOTAL SPACECRAFT WEIGHT. A SIMPLE YET EFFECTIVE SOLUTION AS DISCUSSED IN THE THERMAL MANAGEMENT SYSTEMS ROADMAP IS TO DEVELOP A LIGHTWEIGHT RADIATOR WHICH IS ABLE TO MANIPULATE ITS HEAT REJECTION RATE IN REAL TIME. THIS PROPOSAL DISCUSSES A LIGHT WEIGHT VARIABLE HEAT REJECTION TECHNOLOGY THAT MAY BE UTILIZED IN MANY APPLICATIONS INCLUDING THAT OF A DEEP SPACE RADIATOR. A THIN MIRROR FINISH ALUMINUM FOIL IS FOLDED INTO A SIMPLE ORIGAMI INSPIRED V GROOVE PATTERN. THIS PATTERN ALLOWS FOR THE FOIL TO BE COMPRESSED SUCH THAT THE V GROOVES ARE VERY STEEP AND TIGHTLY COMPACTED OR STRETCHED UNTIL IT RESEMBLES A FLAT SHEET. AS THE FOIL IS COMPRESSED THE AMOUNT OF HEAT RADIATED INTO SPACE OR THE AMOUNT OF HEAT ABSORBED IS GREATLY INCREASED. WHEN PULLED FLAT THE FOIL WILL EMIT AND ABSORB VERY LITTLE RADIATION. THIS VARIABLE HEAT REJECTION CAPABILITY IS USEFUL FOR BOTH RADIATOR AND HEAT SHIELD APPLICATIONS. AS A RADIATOR THE FOIL WILL GIVE THE USER CONTROL OF HOW MUCH HEAT IS ENTERING OR LEAVING THE SYSTEM. THIS TECHNOLOGY WILL ELIMINATE UNNECESSARY RADIATOR WEIGHT WHILE DELIVERING OPTIMUM HEAT REJECTION PERFORMANCE FOR THE ENTIRE MISSION DURATION. LIKEWISE THESE FOILS MAY BE USED AS HEAT SHIELDS PLACED OVER COMPONENTS SENSITIVE TO TEMPERATURE FLUCTUATIONS SUCH AS CRYOGENIC FLUID TANKS. WHEN ILLUMINATED BY THE SUN THE SHIELD CAN ASSUME A FLAT STATE REFLECTING 98 PERCENT OF THE SUN'S ENERGY AWAY FROM THE SENSITIVE COMPONENT. UPON ENTERING THE EARTH'S SHADOW THE SHIELD WILL ASSUME A COMPRESSED STATE EMITTING EXCESS HEAT ORIGINATING FROM THE SPACECRAFT INTO DEEP SPACE INSTEAD OF REFLECTING THIS HEAT ONTO THE CRYOGENIC FLUID TANK.PRELIMINARY WORK CHARACTERIZING THE BEHAVIOR OF V GROOVES WHEN EXPOSED TO RADIATION HAS BEEN COMPLETED. HOWEVER THE BULK OF THE WORK REMAINS. THE TOTAL HEAT REJECTED FROM A FOIL SAMPLE ACCOUNTING FOR EMITTING SURFACE AREA MUST BE CHARACTERIZED. LIKEWISE THE RELATIONSHIP BETWEEN THE FOIL AND THE SURFACE IT IS PROTECTING MUST BE DETERMINED. NEXT AN ACTUATION SYSTEM AND FIXATION COMPONENTS MUST BE DEVELOPED. FINALLY THE COMPLETE THERMAL SYSTEM MUST BE MODELED AND EXPERIMENTALLY PROVEN CAPABLE OF MAINTAINING THE TEMPERATURE OF A PROTECTED SURFACE UNDER VARYING HEAT LOADS. ULTIMATELY THE PURPOSE OF THIS WORK IS TO MODEL A COMPLETE THERMAL SYSTEM INVOLVING THE USE OF A VARIABLE HEAT REJECTION SHIELD DEVELOP THIS TECHNOLOGY TO A SPACE READY STATE AND EXPERIMENTALLY VALIDATE ITS ABILITY TO MAINTAIN THE TEMPERATURE OF A PROTECTED SURFACE WHEN EXPOSED TO VARYING HEAT LOADS.