Introduction to Space Research

Abstract

Our knowledge of the universe comes from the signals we receive at the earth in many forms. For centuries the signals have been detected in the form of visible light, and optical telescopes looking out into space-to the Sun, the moon, the planets and myriads of stars and galaxies have opened up new vistas of the universe. To these another kind of signal was added in the 1930’s with the discovery of radio waves coming from astronomical objects which ushered the new branch of radio astronomy. However, it was realized that besides the optical and radio bands received at the surface of the earth, the vast expanse of the electromagnetic spectrum remained hidden from us because of the protective blanket of the earth’s atmosphere which absorbs most of these electromagnetic waves. In the past decades scientists were able to send instruments in space vehicles to progressively higher altitudes in the atmosphere and finally with satellites completely outside the earth’s atmosphere. These unveiled dramatically new vistas of the near-earth space, the interplanetary medium and of the distant interstellar space, which reveiled to be populated by new kinds of plasmas, particles and magnetic fields, as well as energetic nuclei, ions and cosmic rays. Also scientists were able to look at the Sun, the planets, the stars and the galaxies at several different wavelengths of the electromagnetic spectrum such as ultraviolet soft x-rays, hard x-rays and gamma rays and thus obtain a strikingly new picture of them. Thus new astronomies were born, i.e.. ultra-violet, x-ray and gamma ray astronomies which rapidly expanded in many dimensions and became new disciplines of astrophysics and space science. We shall briefly trace the growth and developments of these exciting new achievements in space physics and space astrophysics in this chapter and thus bring to focus new perspectives in these cosmic phenomena.