ACS - Advanced Camera for Surveys - The Advanced Camera for Surveys (ACS) is a third-generation imaging camera. This camera is optimized to perform surveys or broad imaging campaigns.
NICMOS - Near Infrared Camera/Multi-Object Spectrometer - Second-generation imager/spectrograph. NICMOS is Hubble's only near-infrared (NIR) instrument. To be sensitive in the NIR, NICMOS must operate at a very low temperature, requiring sophisticated coolers. Problems with the solid nitrogen refrigerant have necessitated the installation of the NICMOS Cryocooler (NCC) on SM3B to continue its operation.
STIS - Space Telescope Imaging Spectrograph- Second-generation imager/spectrograph. STIS is used to obtain high resolution spectra of resolved objects. STIS has the special ability to simultaneously obtain spectra from many different points along a target.