... 13, Moscow 119992, Russian Federation, e-mail: busarev@sai.msu.ru; 2 Research Institute Crimean Astrophysical Observatory, p/o Nauchnyi, Crimea 334413, Ukraine, e-mail: prok@crao.crimea.ua Summary: We propose a combined method of astronomical investigations of small or distant planets incorporating registration of a set of integral spectra of an object and their frequency analysis. ... An application of the method is shown on example of asteroid 21 Lutetia. ... 6] Busarev V. V. (2002), Solar Sys. ...