The early days of gamma-ray astronomy.

The aims of gamma-ray astronomy were to establish both, the sources of cosmic rays and the seats of nucleosynthesis. The 1950's could be called the decade of predictions, when both roots came together and source strengths were predicted on the basis of radio-astronomical data and expectations of steady state cosmology. The 1960's were the decade of disappointment, because detectors employed then had too little sensitivity and too high background. The 1970's, the decade of discoveries were opened with OSO III seeing the milky way in gamma-rays, followed by SAS 2, Cos-B, SMM and others. And the 1980's were the decade of preparation for the Compton gamma-Ray Observatory: by now, gamma-ray observation have turned into a real astronomy and many of the original hopes have been fulfilled.