Mirror blank made for FUSE (Far Ultraviolet Spectroscopic Explorer ) a space-based telescope satellite, used in the run up to the flight's launch in 1999. This engineering blank was used to test the computer-controlled light-weighting technique (the carving out of the honeycomb structure in the back of the mirror to make it lighter) at John Hopkins University and NASA Goddard Space Flight Center.

This mirror segment has been left without its reflective coating to reveal its lightweight glass-ceramic structure. It was used in developing NASA’s FUSE satellite. During its eight-year run, each of FUSE’s four mirrors collected ultraviolet light emitted by gas atoms in deep space and focused them onto the spacecraft’s detector.

FUSE mapped the distribution of deuterium, a heavy type of hydrogen formed during the Big Bang. By measuring how much deuterium still exists, scientists can learn more about how the young universe evolved.