The Origins Space Telescope (OST) is an initiative to develop a space telescope in the 8 to 15 diameter meter range, in an L2 orbit, to observe infrared wavelengths in the 5 μm to 1 mm range, for launch roughly 2035. It is to aim at high redshifts as well investigation of solar system objects such as comets, and extra-solar planet observations.
At present, concepts are being developed, the first (now called Concept 1) for a 9.1-meter primary mirror, and instruments including camera(s), spectrograph(s) and polarimeter(s) covering 5 to 660 μm, with instruments cooled to 5 K to reduce thermal noise, thus increase sensitivity. This wavelength-range is similar to Herschel Space Observatory but it would have far more sensitivity due to the cryogenic temperature.
Concept 2 is for a less-ambitious project accommodating a smaller budget. One practical concern addressed is the launch size and weight, reducing the telescope's mass and dimensions so as to be launched by the SLS 8.4-meter-diameter launch rocket, currently in development. The telescope would cover the same wavelength range with similarly sensitive instruments cooled to 5 K. The primary mirror size would match James Webb Space Telescope-size (6.5-meter) or would be somewhat smaller, but would be larger then Herschel (3.5-meter). The sensitivity offered by the 5 K temperature is considered the primary advantage over earlier similar telescopes.