Precision radiometric calibration of space-borne instruments in the spectral region from UV through FIR based on the use of fixed-point blackbodies

The solution of problems within the nine major directions of research formulated in the 10-year implementation plan for the Global Earth Observation System of Systems (GEOSS) requires that the measurements conducted by all its systems be traceable to a single standard source. The highest requirements for the radiometric measurements follow from the climatology objectives, which include accumulation of data over the time spans of decades. The required accuracy and long- term stability of measurements are • 0.1% and 0.02% per decade within the spectral region from 0.2 µm to 3 µm; • 0.1K and 0.01K per decade within the spectral region from 3 µm to 15 µm. The standard sources required for this level of accuracy and stability should be better than what is available at this time for calibration of space-borne radiometric instruments. Improving the standard sources is one of the objectives pursued by the All-Russian Research Institute for Opto-Physical Measurements as part of its efforts to develop high stability and high accuracy black bodies based on the phase transitions of: • Metal/carbon eutectic (for the 0.2 µm to 3 µm region), and • Pure metals (for the 3 µm to 15 µm region). The report contains a description of the physics and principle design of these radiation sources, a list of models developed by the Institute as well as results of their experimental studies. The unique reproducibility of these radiation sources that is based upon the constancy of the phase transition physical properties along with the ability to reproduce many identical sources based on the phase transition principle opens up a way to develop a single stable radiometric scale for the GEOSS. I. PROBLEM FORMULATION