The Orbiting Retrievable Far and Extreme Ultraviolet Spectrometers (ORFEUS)-SPAS payloads were joint DARA (German Space Agency)/NASA missions flown on two shuttle flights. The first flight was September 12-22, 1993 aboard the shuttle Discovery. The second flight, aboard Columbia, was from November 19, through December 7, 1996.

The free-flying ORFEUS-SPAS platform was designed to be deployed and and retreived from the shuttle.

The three instruments on the ORFEUS were designed to provide astronomical ultraviolet spectroscopic observations over the wavelength range from 40 to 140 nanometers. The three instruments were:

• Tübingen Ultraviolet Echelle Spectrometer (TUES); (PI) Prof. Michael Grewing; University of Tübingen
  
  
• Berkeley Extreme and Far-UV Spectrometer (BEFS); (PI) Dr. Mark Hurwitz; University of California, Berkeley. This instrument was called the Extreme Ultraviolet (EUV) Spectrometer in the ORFEUS-SPAS II Mission Research Announcement. It was later renamed.
  
  
• Interstellar Medium Absorption Profile Spectrograph (IMAPS); (PI) Dr. Edward Jenkins; Princeton University

The largest science instrument onboard was a 1-meter telescope. The telescope primary was coated with iridium to improve its light gathering power in the ultraviolet. Incoming light was focused to a movable mirror which deflected the light rays into the FUV Spectrometer (i.e., TUES), which operated in the 90-140 nanometer range. When the pick-off mirror was moved out of the beam, light fell instead onto the BEFS Spectrometer, which covered wavelengths between 39 and 120 nanometers. A second, separate instrument, the IMAPS Spectrograph, recorded extremely high resolution spectral data in the 95-115 nanometer range.

This information came from the ORFEUS-SPAS II Mission Research Announcement. A postscript version of this research announcement is located in /archive.stsci.edu/pub/pub/orfeus/orfeus_nra.ps