The 2.4-meter Space Telescope (ST), to be launched in 1983, will provide the first opportunity for astronomers to fully exploit the observing environment above the Earth's atmosphere. The absence of atmospheric turbulence and scintillation, air glow, and absorption in the ultraviolet and infrared spectral bands will permit the observation of a greatly increased volume of space, and studies of nearby objects with finer angular and temporal resolution, higher photometric accuracy, and broader spectral coverage than has been possible heretofore. A group of five powerful and versatile scientific instruments will be used to conduct the initial observations from the ST observatory --a wide-field and planetary camera, a faint-object camera, a faint-object spectrograph, a high-resolution spectrograph, and a high-speed photometer. Also, astrometric observations will be obtained with the ST fine-guidance sensors. This paper briefly describes the ST observatory, outlines the design concepts of the five scientific instruments, and summarizes their astronomical capabilities.