Skobeltsyn Institute of Nuclear Physics
Lomonosov Moscow State University

The proton spectra, measured by the ATIC instrument in a broad energy range and reported by the Maryland University (MU) and Moscow State University (MSU) teams, are discussed. It is shown, that the MSU spectrum is in good agreement with the proton spectrum having a 'knee' at energies of ~2 TeV and the spectrum, measured on the 'Proton' satellite. The MU spectrum differs from the MSU spectrum and does not have a 'knee'. The possible reasons of such discrepancies between the MU and MSU spectra are discussed. It is shown that the possible reason for such discrepancies can be the backscattered particles arriving in the charge detector from the calorimeter. If the backscatter is taken into account the MSU and MU results can be brought to quantitative agreement.