STIS resides in an axial bay behind the Hubble main mirror. STIS is nearly seve feet by three feet by three feet and weighs over 800 pounds. The instrument is designed to work in three different wavelength regions, each with its own detector. Scientists using STIS focus their science on many areas, including the search for massive black holes; the measurement of distribution of matter in the universe; the study of stars forming in distant galaxies; and the imaging of large (Jupiter-sized) planets around nearby stars.

The STIS instrument provides enhanced capabilities over the two original spectrograph instruments. STIS covers a broader wavelength range with two-dimensional capability, adds a coronograph capability, and has a high time-resolution capability in the ultraviolet. This instrument also images and provides objective prism spectra in the intermediate ultraviolet.