The Origins Space Telescope (OST) is an initiative to develop a 2030s large-aperture space telescope, in an L2 orbit, to observe infrared wavelengths in the 5 μm to 1 mm range, for launch roughly 2035. Its goal is high redshifts as well investigation of solar system objects such as comets, and extra-solar planet observations. Given the far-future time-frame, the concepts have been shifting and can be expected to shift more.
Current plans are a 5.9-meter aperture (similar to that of James Webb Space Telescope), with instruments including camera(s), spectrograph(s) and polarimeter(s) covering 2.8 to 588 μm, with instruments cooled to 4.5 K to reduce thermal noise, thus increase sensitivity. This wavelength-range is similar to Herschel Space Observatory but with an aperture larger than Herschel's 3.5 meters and with far more sensitivity due to the cryogenic temperature. Instruments:
Initial plans aimed for an aperture in the 8-15 range, and an early concept specified a 9.1-meter primary mirror. This came to be termed Concept 1, with the name Concept 2 applied to the plan that continues to evolve, which addresses budget concerns, among them, matching its dimensions to practically-available launch equipment, aiming to match the capabilities of the SLS 8.4-meter-diameter launch rocket currently in development, or hoping some future launch vehicle will have similar capabilities.