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. We apply new NIST micromachining fabrication and carbon nanotube capabilities to miniaturize ambient-temperature radiometer designs for measurements of Earth’s radiation budget. With the capabilities of these new techniques and materials, we will evaluate new radiometer designs to acquire measurements of incoming and outgoing Earth radiation from small spacecraft. Miniature ambient-temperature radiometers will be designed, fabricated, and demonstrated over the broad range of requirements encompassed by Earth-incident total and spectral solar irradiance measurements, as these span the performance requirements of Earth radiation measurements for climate studies. CAESR test radiometers will be validated using international reference facilities and compared to the performance of current flight radiometers. The CAESR carbon nanotube coatings and micromachining techniques are expected to reduce instrument mass and size and decrease power needs, enabling the acquisition of such measurements from small spacecraft platforms. Integrated fabrication techniques should also greatly improve manufacturing efficiencies and yield from current flight radiometers to reduce instrument delivery times (and thus costs). The CAESR TRL entry is 2 and exit is 4, readying these compact radiometers for instrument developments on small spacecraft by the end of the 3-year program commencing in Jan. 2015.