In February 1997 a second servicing operation (HST SM-02) was successfully accomplished by the STS-82 space shuttle Discovery mission. As part of this HST servicing mission, astronauts installed the Space Telescope Imaging Spectrograph (STIS) and the Near-Infrared Camera and Multi-Object Spectrometer (NICMOS). These instruments replaced the Goddard High-Resolution Spectrograph (GHRS) and the Faint Object Spectrograph (FOS), respectively. The STIS observes the universe in four spectral bands that extend from the ultraviolet through the visible and into the near-infrared. Astronomers use the STIS to analyze the temperature, composition, motion, and other important properties of celestial objects. Operating at near-infrared wavelengths, the NICMOS is letting astronomers observe the dusty cores of active galactic nuclei (AGN) and investigate interesting proto-planetary disks around stars.
