Like all disciplines in opaque bands of the Earth's atmosphere, X-ray astronomy is still quite young. Following some early balloon experiments, the first X-ray satellites had to wait for rockets to be available for launching them into orbit. X-ray observations opened up a previously unknown part of the Universe dominated by hot electrically charged gases (plasmas) and highly energetic sources (such as the immediate surroundings of black holes). The "father of X-ray astronomy" is Nobel prize winner R. Giacconi.
Since the 1960s a few generations of X-ray satellites have been in orbit.