Such sensors work exactly the same way that optical sensors but in a wider spectrum. They are furthermore able to provide intensity for elementary spectrum bands. They enable to characterize soils thanks to their spectral signatures. It requires post-processing of the imagery. Limitations: soil signatures have to be different enough. But they can depend on several parameters.
Reference: “Automated monitoring of snow cover over North America with multispectral satellite data,” J. Appl. Meteorol., vol. 39, no. 11, pp. 1866–1880, Nov. 2000 (P. Romanov, G. Gutman, and I. Csiszar).