Spectrograph, Faint Object, Hubble Space Telescope (FOS)

The Faint Object Spectrograph (FOS), one of the original axial instruments launched with the Hubble Space Telescope (HST) in April 1990, provided confirming evidence for a massive black hole in 1994 in the giant elliptical galaxy M87. It also engaged in many other observing programs, observing individual stars in other galaxies as well as the impact of Comet Shoemaker-Levy 9 on Jupiter. But most significantly it refined quantitative measurements of the characteristics of massive black holes from studies of accretion disks at the centers of galaxies. After almost seven years of service, FOS was removed from HST on February 13, 1997 by the Space Shuttle crew (STS 82, Discovery) during a servicing mission to provide room for a new instrument. The instrument was transferred to NASM by NASA's Goddard Space Flight Center in 1999. It is now on display in the Explore the Universe gallery.