Validating Instrument Models Through the Calibration Process

The performance of modem IR instruments is becoming so good that meeting science requirements requires an accurate instrument model be used throughout the design and development process. The huge cost overruns on recent major programs are indicative that the design and cost models being used to predict performance have lagged behind anticipated performance. Tuning these models to accurately reflect the true performance of target instruments requires a modeling process that has been developed over several instruments and validated by careful calibration. The process of developing a series of Engineering Development Models is often used on longer duration programs to achieve this end. The accuracy of the models and their components has to be validated by a carefully planned calibration process, preferably considered in the instrument design. However, a good model does not satisfy all the requirements to bring acquisition programs under control. Careful detail in the specification process and a similar, validated model on the government side will also be required. This paper discusses the model development process and calibration approaches used to verify and update the models of several new instruments, including Geosynchronous Imaging Fourier Transform Spectrometer (GIFTS) and Far Infrared Spectroscopy of the Troposphere (FIRST).