This is a thermal test chamber used in connection with the Celescope project to test and calibrate the electronic detector elements, the critical components in the program. Celescope was a satellite-borne telescope developed at the Smithsonian Astrophysical Observatory in the 1960s to survey the entire ultraviolet sky, looking for unusually hot sources of energy. The SAO Celescope consisted of four individual 12-inch reflecting telescopes. The signal from the telescopes was telemetered back to a ground station where it was used to construct a map of ultraviolet sources in the sky. The telescope was flown on December 7, 1968 as part of the payload for the second Orbiting Astronomical Satellite. The data from Celescope resulted in a catalog of over 5,000 ultraviolet colors for stars.

This test chamber was transferred to NASM from SAO in 1973.