In spite of the title of this paper, it is not easy to point out many significant developments in the techniques of space radio-astronomy in the last few years. Radio-astronomers are limited in their endeavours by several difficulties which they have not yet been able to overcome completely. I still remember F.G. Smith, in his 1965 Liège Symposium talk, saying that “space radioastronomy is in great danger of turning to geophysics”. This statement seems still valid three years later.
However, we might consider that this tendency to deal with geophysical phenomena more than with observations of real astrophysical significance, is after all, not so bad. First of all, it is becoming more and more difficult to define the boundary between geophysics and astrophysics. And second, the Earth environment can be used as a laboratory where a number of processes which are assumed to take place in celestial bodies can be studied in situ. Some types of radio emissions observed by space telescopes are still to be explained and could very well lead to the understanding of mechanisms overlooked by the theoreticians. Radiophysical methods make a very powerful tool to study these phenomena, which occur in a medium that is now being extensively probed by rockets and satellites which send a continuous flow of data to the Earth, about 100000 bits per second, according to Parker.