The Advanced Solidstate Array Spectroradiometer (ASAS) is an airborne imaging spectrometer with 30 spectral channels extending from 450 to 880 nm. A 32 x 512 element silicon Charge Injection Device (CID) array is used as the detector. The ASAS was developed at the NASA Johnson Space Center (JSC) with General Electric providing the detector package under funding from the Naval Ocean Systems Center. The instrument was transferred to NASA Goddard Space Flight Center (GSFC) after its completion and initial test flights in August 1983. Several changes and refinements have been made to the ASAS as a result of the use of this instrument for terrestrial and oceanographic remote sensing research. The most notable of these changes has been in the sensor (optics plus detector package) mounting technique. This changed the ASAS from a fixed nadir viewing instrument to a sensor capable of multiple direction observations of surface bidirectional reflectance distribution functions. This change and refinements in the ability to radiometrically and spectrally calibrate the ASAS as well as reliability improvements are presented.