Abstract We propose to establish an Orbital Stellar Stereoscopic Observatory (OStSO) consisting of two identically equipped spacecrafts (SCs) in the vicinity of two Lagrangian libration points, L4 and L5, of the “Sun – Earth+Moon barycenter” system. The stereoscopic baseline length is B = a 3 ≈ 259.111 $B = a\sqrt 3 \approx 259.111$ million km (86.4% of the Earth orbit diameter). Each of the two Tsukanova–Korsch three-mirror astrographs has an aperture of 1m and focal length of 30 m; the focal-plane CCD array is 350 mm in diameter. The expected astrometric accuracy is ±0.0007″ in a single measurement. Each frame in the scientific program is captured synchronously by the two astrographs, allowing to obtain instantaneous parallaxes of stars as far as up to 5 kpc, along with spectral energy distributions (SEDs) of point and extended sources in the Tholen filter system (Zellner et al. 1985) extended to 12–14 bands, including the integral one. We expect the project to provide a large amount of important information for stellar astronomy and for various studies of Galactic objects.