THE LONG-TERM BALANCE BETWEEN EARTH S ABSORPTION OF SOLAR RADIATIVE ENERGY AND EMISSION OF RADIATION TO SPACE IS A FUNDAMENTAL CLIMATE MEASUREMENT REQUIRED IN THE NRC S DECADAL SURVEY REPORT EARTH SCIENCE AND APPLICATIONS FROM SPACE: NATIONAL IMPERATIVES FOR THE NEXT DECADE AND BEYOND. TOTAL SOLAR IRRADIANCE (TSI) HAS BEEN MEASURED FROM SPACE BY A 40-YEAR UNINTERRUPTED SEQUENCE OF INSTRUMENTS. WE PROPOSE TO BUILD AND FLY A NEXT-GENERATION TSI INSTRUMENT ON A 6U CUBESAT THE COMPACT TOTAL IRRADIANCE MONITOR (CTIM). THIS INSTRUMENT WILL MEET THE MEASUREMENT REQUIREMENTS OF THE PREVIOUS GENERATION INSTRUMENTS WHILE BEING COMPACT ENOUGH TO FIT ON CUBESAT PLATFORM. IN ORDER TO ACCOMPLISH THIS THE CTIM WILL UTILIZE NEW TECHNOLOGIES INCLUDING SILICON-BASED VERTICALLY ALIGNED CARBON NANOTUBE (VACNT) BOLOMETERS. THE GOAL OF THIS PROGRAM IS TO DEMONSTRATE AND RAISE THE TRL OF NEXT-GENERATION TECHNOLOGY WHICH WILL PERMIT THE MEASUREMENT OF TSI FROM A CUBESAT PLATFORM. THIS COMPACT LOWER-MASS INSTRUMENT HAS SHORTER FABRICATION TIMES AND LOWER COSTS WHICH SHOULD PROVIDE MORE FLIGHT OPPORTUNITIES HELPING REDUCE THE RISK OF FUTURE TSI-MEASUREMENT DATA GAPS. THIS PROGRAM WILL RUN FROM SEPTEMBER 17 2018 THROUGH SEPTEMBER 17 2021. WE WILL FIRST REBUILD KEY ELEMENTS OF THE CTIM INSTRUMENT DEVELOPED DURING THE CTIM INSTRUMENT INCUBATOR PROGRAM (IIP) PROGRAM INCORPORATING LESSON LEARNED FROM THE ENVIRONMENTAL AND PERFORMANCE TESTING OF THE CTIM. WE WILL THEN PROCURE AND INTEGRATE A BLUE CANYON TECHNOLOGIES XB1 CUBESAT BUS. THE INTEGRATED SYSTEM WILL UNDERGO ENVIRONMENTAL PERFORMANCE AND END-TO-END TESTING. THE TARGET LAUNCH DATE OF THE CTIM-FD IS SEPTEMBER 2020. THE PLANNED ONE-YEAR MISSION WILL TEST THE ON-ORBIT PERFORMANCE OF THE CTIM-FD DIRECTLY AGAINST TOTAL AND SPECTRAL SOLAR IRRADIANCE SENSOR (TSIS) TOTAL IRRADIANCE MONITOR (TIM) CURRENTLY OPERATING ON THE INTERNATIONAL SPACE STATION. DURING THIS MEASUREMENT WE WILL TEST THE INITIAL MEASUREMENT ACCURACY OF THE CTIM AND THE LONG-TERM STABILITY OF THE MEASUREMENTS OVER THE MISSION LIFE. THE CTIM ENTRY TRL IS 5 BASED ON PROTOTYPE TESTING WORK PERFORMED ON THE CARBON ABSOLUTE ELECTRICAL SUBSTITUTION RADIOMETERS (CAESR) ADVANCED COMPONENT TECHNOLOGIES (ACT) PROJECT AND THE RELATED COMPACT SPECTRAL IRRADIANCE MONITOR (CSIM) IIP PROJECT. THE PLANNED EXIT TRL IS 7-9 BASED ON SUCCESSFUL ON-ORBIT OPERATIONS.