In preparing for future L band soil moisture satellite missions, investigators have employed ground, aircraft and satellite sensors. Of the satellite sensors, there has been only one instrument that provides any heritage at L band, the Skylab S-194 instrument that operated in the 1970s. Data from theses missions have been analyzed and reported in a few applications, however, these studies utilized either the linear regression approach or the Antecedent Precipitation Index (API). We explore the use of products from climate model reanalysis projects as ancillary data to exploit the S-194 data for a broad range of soil moisture conditions by employing a radiative transfer approach. The spatial resolution and the accuracy of reanalysis outputs are major limitations to this approach.