The Radiation Budget Instrument (RBI): A New Standard for Measuring the Earth's Radiation Balance

For the past three decades, the ERBE and CERES instruments have established a long-term data record for the total radiance being emitted and reflected from the Earth. This data record is critical to understanding the Earth's radiation balance, which in turn is a key driver to climate change. NASA has recently selected Exelis to build the follow-on instrument which will continue the ERBE/CERES data records into the future. This new instrument is called the Radiation Budget Instrument, or RBI. Its first flight will be on the JPSS-2 satellite, which is planned for launched in 2021.

RBI measures upwelling Earth radiance over an extremely broad spectral range, from the ultraviolet (0.3 microns) to the far-infrared (100 microns), separated into three spectral bands. RBI includes advanced onboard calibration sub-systems which ensure the highly precise radiometric accuracy and precision that are required to fulfill the radiation balance mission. RBI leverages existing flight-proven designs for many of its components; most of these components are taken from the successful Cross-track Infrared Sounder (CrIS) instrument, which has flown on the S-NPP satellite since 2011.

This paper will describe the RBI mission, the key requirements for the RBI instrument, and the overall instrument design approach to be used. This includes details of the onboard calibration targets, optical design, and detector approach. Projections of RBI performance against the key requirements will also be discussed. This includes a description of the calibration approach to be used for setting the initial ground calibration (performed at Space Dynamics Laboratory), and then holding that calibration throughout mission life using the onboard calibration sources. RBI development plans and schedules will also be discussed.