The spacecraft environment is discussed according as the optical circumstances and the spectrometer (SPC) onboard Space Flyer Unit (SFU) is reported. The optical researches have been performed in experimentally and theoretically since 1960's and accelerated on Space Shuttle missions. Especially, the investigation of "Shuttle Glow" became great topics. Moreover, the existence of secondary ion beams and the electromagnetically turbulence around the orbiter were found. The SFU is now planned and to be launched in 1990's. An Environmental Diagnostic Package (EDP) is planned on SFU. This is designed to study the spacecraft environment, systematically. The spectrometer (SPC) on EDP is designed to investigate the optical phenomena such as the Shuttle Glow as one of diagnostic equipment connect with another observation methods and also the optical properties of test pieces used in the space. The SPC is based on the commercial monochromator (JASCO CT-10) and its spectral covering range is 3000-8000 A with resolution of 25 A, and its aperture ratio is F 3.0. This report shows some of optical observing targets and a master plan of spectrometer (SPC) which is to be used in the EDP first mission.