For some years, the European Space Agency (ESA) has offered European students the opportunity to carry out experiments in microgravity. In 2000, ESA selected 30 experiments including ours. Our experiment consisted in comparing the bacteria centrifuged at 15'000 g and fixed in microgravity, with identical cells in normal gravity, in order to observe the influence of terrestrial gravity in the reorganization of the internal structure of the prokaryotic cell. For this purpose, the chromosome of the cells was colored with DAPI which allowed examination by fluorescence microscopy. Differences between samples fixed in gravity zero and normal gravity seem to show that bacteria use terrestrial gravity as a reference in reorganizing their internal structure after an acceleration corresponding to the impact of a small meteorite hitting an ocean on the earth surface