The Multispectral Thermal Imager (MTI) is designed to demonstrate the utility of multispectral remote sensing from a satellite platform for a variety of applications of interest to the U.S. Department of Energy. These applications include characterization of industrial facilities, environmental impacts of effluents, global change, hazardous waste sites, resource exploitation, crop health, and others. The MTI was designed using a procedure which we call `End-to-end modeling and analysis (EEM).' We began with target attributes, translated to observable signatures and then propagated the signatures through the atmosphere to the sensor location. We modeled the sensor attributes to yield a simulated data stream, which was then analyzed to retrieve information about the original target. The retrieved signature was then compared to the original to obtain a figure of merit: hence the term `end-to-end modeling and analysis.' We based the EEM in physics to ensure high fidelity and to permit scaling. As the actual design of the payload evolved, and as real hardware was tested, we updated the EEM to facilitate trade studies, and to judge, for example, whether components that deviated from specifications were acceptable. During detailed calibration at the Los Alamos Radiometric Calibration Facility we used our models to explain certain observations, and to extend limited measurements to larger domains of applicability. Data analysis programs have been developed to generate a comprehensive set of data products through our Data Processing and Analysis Center. The satellite was due for launch on 8 February 2000: the actual launch data was 12 March, 2000. At the conference we anticipate sharing some preliminary observations from on-orbit.