Recent observations of the leading and trailing hemispheres of Europa and Callisto and the leading hemisphere of Ganymede were carried out in the wavelength range from 1. 0 to 2. 5 m with the 2. 5 -m telescope at the Caucasus Mountain Observatory of Sternberg Astronomical Institute, Lomonosov Moscow State University. The aim of the work was to search for spectral absorption features of new compounds or processes of mass character on the surfaces of these similar in origin bodies. We confirmed our previous detection in the reflectance spectra of Europa (in the leading and trailing hemispheres) 1 of an absorption band centered at 1. 64-1. 67 m and its interpretation as a feature of CH ₄ clathrate. However, presently the band turned out to be larger in intensity and half-width. Additionally, a similar spectral feature was detected for the first time in reflectance spectra of Ganymede’s leading hemisphere. So, we assume a common character of this spectral detail and its probable variability on Europa and Ganymede.
Busarev et al. (Mon,) studied this question.