The analytical second-order theory of the motion of an arificial satellite in the Earth’s atmosphere is used to determine the satellites’ lifetime. The analytical theory is unique in the sense that it determines the secular changes of the semi-major axis and the eccentricity for a longer time-interval, characterized by the time of revolution. To establish the analytical theory, a special thermospheric model is used, which expresses directly the thermospheric total density. The theory is developed to the
second-degree in small parameters (coefficients of the density model); this enables to determine analytically the changes of the elements over an interval of several days. The gravitational effects of the Earth’s oblateness are taken into account, too. The whole theory is used for the lifetime determination of the satellite "CESAR" supposed to be launched in 1997.
We report on the measurement of the lifetime of muons coming from cosmic rays using a simple apparatus consisting of a scintillator, photomultiplier and an oscilloscope. The measured muon lifetime is (2,13 ± 0,21 (stat) ± 0,16 (syst)) μs, which is in agreement with the published average value. The measured lifetime was used to calculate the Fermi constant of weak interactions, which resulted in (1,18 ± 0,06 (stat) ± 0,04 (syst))·10-5 GeV-2, again in agreement with other experiments. and Prezentujeme návrh a provedení experimentu měření doby života mionů pocházejících z kosmického záření s použitím jednoduché aparatury složené ze scintilátoru, fotonásobiče a osciloskopu. Ze změřené doby života mionu (2,13 ± 0,21 (stat) ± 0,16 (syst)) μs byla vypočtena Fermiho konstanta slabé interakce o velikosti (1,18 ± 0,06 (stat) ± 0,04 (syst))·10-5 GeV-2, obě veličiny jsou v souladu stabelovanými hodnotami.