This is the flight primary mirror from Stratoscope I, a 12-inch balloon-borne reflecting telescope designed to provide high-resolution observations of the photosphere of the sun from a stable platform above the densest part of the atmosphere. It was conceived and led by Martin Schwarzschild of Princeton University, who wanted to make observations that would help him understand the nature of turbulence in the photosphere of the sun. Stratoscope was built in 1957, and after several flights it was dismantled. The platform was given to the National Center for Atmospheric Research for coronagraphic flights, and the primary mirror was preserved at Princeton. The telescope and its optics were designed and built by the Perkin Elmer Corporation. The sun acquisition and pointing mechanism was constructed by the Research Service Laboratories at the University of Colorado.
Princeton University donated the mirror to NASM in June 1982.
This object is not on display at the National Air and Space Museum. It is either on loan or in storage.