The Spitzer Space Telescope is the final mission of NASA's Great Observatories Program. Launched in August 2003, Spitzer completes a decade of exploration across the spectrum, providing unparallelled sensitivity in seeing the infrared universe.

Three scientific instrument packages are onboard. Two, the InfraRed Array Camera and the Multiband Infrared Photometer for Spitzer, take pictures of the sky in infrared radiation. The third is the subject of these pages.

The Infrared Spectrograph consists of four separate instruments which take fingerprints of the infrared radiation emitted by distant objects. Pairs of modules work respectively in the near and mid infrared. Each pair contains a low resolution instrument and a high resolution instrument, optimized for objects of different brightness and for different types of scientific observations.

The Spitzer mission is a collaborative effort involving NASA, JPL, CalTech, Ball Aerospace, Lockheed Martin, the University of Arizona, the Harvard Smithsonian Astrophysical Observatory, and Cornell University.

The Infrared Spectrograph or IRS was built by Ball Aerospace under contract to JPL and Cornell University based on designs and prototypes constructed at Cornell. This is its story.