X-ray astronomy missions.

The principal accomplishment of the X-ray astronomy space missions, including sounding rockets and balloons, are reviewed in an attempt to illustrate their roles in the development of the field over the past 30 years. Attention is given to the early rocket missions (1962-1969), the small satellite era (1967-1977), and the large HEAO missions (1977-1981). X-ray astronomy missions during the 1980s are discussed with particular reference to Ariel-6, Exosat, and the Japanese and Soviet programs. Finally, the 1990s missions and some missions expected to be launched in the current decade are summarized.