On October the 4th, 1957, the world was startled by the announcement that the Russians had put a satellite, Sputnik I, successfully into orbit. The launching, coupled with the relatively large size of the satellite, caused widespread alarm in the United States. The Americans had already announced their intention of launching a number of small satellites as part of their contribution to the International Geophysical Year, which began in July 1957. Practically the only hint that the Russians intended anything similar was given by an article in a Soviet magazine for Radio amateurs, which in July 1957 asked enthusiasts to prepare receiving systems in the 20 and 40 Megacycle Bands for satellite reception, laid down the form in which observations should be taken, and gave a telegraphic address, Moskva-Sputnik, to which they should be sent. This article passed unnoticed in the West.

Five years later, with more than too successful launchings of satellites and space probes, it is possible to attempt some assessment of the scientific contribution made by these experiments. In some fields it has been very significant, in others disappointingly small, serving mainly to confirm what had already been inferred by indirect methods. The number of spectacular discoveries has been very small indeed.

Sputnik I was a sphere, about 23 inches across, and weighing 184 lbs. Its rocket carrier, weighing four tons, went into the same orbit. It carried two radio transmitters of fairly high power, which continued to transmit for about three weeks. As far as is known, it had no scientific instruments apart from those which monitored conditions inside the satellite, and the only scientific publications resulting from this flight have been those concerned with the satellite path, and the effects of atmospheric drag. Sputnik II, which went into orbit on November 3rd, was heavier and more sophisticated.