The Cosmic Origins Spectrograph, a fourth-generation instrument, designed by Dr. James Green and his University of Colorado colleagues for the cosmic web study in the 90's, will replace the Corrective Optics Space Telescope Axial Replacement (COSTAR.)
Once installed on the Hubble Space Telescope during the upcoming servicing mission this year, COS will dramatically advance physics and astrophysics research on the origin of the Universe, astronomical objects, evolution of galaxies, and planetary system formations. In addition, the spectroscope will significantly enhance the spectroscopic capabilities of the telescope at ultraviolet wavelengths, provide scientists with unparalleled opportunities for observing faint sources of ultraviolet and cosmic web light that will absorb new cosmic information and help the telescope investigate the collected data until the end of its mission, currently 2013.
Wide-Field Planetary Camera 2 (WFPC2) was installed in Dec 1993 and used to obtain high resolution images of astronomical objects. This camera was removed in the last servicing mission so it is no longer in service.