Within the framework of any Space Surveillance and Tracking activities, the capability of optical sensors to perform spectroscopic observations would add a unique value to acquiring supplementary information on any extemporary object crossing the telescope field of view. In addition to the astrometric information, probing the body’s albedo via low-resolution spectroscopy would constrain the geometry and physical nature of the target and discriminate among spent rocket parts, coarse debris and intact spacecraft. The EU-SST project SuperFOSC, currently in progress at INAF-OAS, is a one square degree wide-field camera that will equip the “G.D. Cassini’” telescope, located close to Bologna (Italy). Besides the imaging capabilities, we also envisage an option to secure one-shot slit-less spectroscopy of all the (censed and uncensed) objects crossing the telescope field of view along with the observations of the bonafide planned targets. This will be done by placing a diffractive grism on a pupil image inside the camera. This paper investigates the system performance in terms of spectral resolution as a function of the intruding object(s) path for a grism with a fixed or variable position angle. In addition, as an innovative concept, we also discuss a three-faces grism (Trism) solution to catch any source three spectra at a time, each 120 deg apart in position angle on the sky, to maximise spectral resolution disregarding object trajectory. An added value of our Trism solution would be avoiding moving optical parts inside the instrument with a significantly improved image quality.