Abstract—The ultraviolet wavelength range (90-300 nm) is one of the most important parts of the electromagnetic spectrum for astrophysicists. The success of the GALEX and ASTROSAT/UVIT missions has given a new view on the ultraviolet sky with unprecedented detail of extended objects, such as planetary nebulae or supernova remnants. Direct images of the sky allow us to track the morphology of such objects, but provide very limited information about their physical conditions: temperature, density, and radiation fields. Spectroscopic observations make it possible to study local physical conditions, but usually only at one point in an extended nebula. Our proposed long-slit spectrograph (SING, Spectroscopic Investigation of Nebular Gas) will allow tracking emission lines across the entire spatially extended nebulae in the wavelength range of 140-270 nm, which is the key to understanding their dynamics and evolution. The spectrograph will operate onboard the Chinese space station. The article describes the scientific tasks for which this unique device is created, its main characteristics and preliminary design.