Radiation Budget Instrument On-Board Solar Calibration Target-Concept and Operation

The Radiation Budget Instrument (RBI) on-board Solar Calibration Target (SCT) concept and operation are presented in this paper. The SCT used during solar calibration of RBI is based on reflection properties of sintered Polytetrafluoroethylene (PTFE), an extremely stable, near perfect, Lambertian diffuser. The SCT incorporates three identical space grade sintered PTFE diffusers for on-orbit degradation monitoring. The SCT is used for calibration of the Shortwave $(0.3-2.5 \mu \mathbf{m})$ and Total $(0.3-100+ \mathbf{\mu} \mathbf{m})$ channels of RBI. System level calibration test design and pre-flight calibration of each diffuser is also presented.