ULTIMA free-flying large-aperture space telescope

Project ULTIMA is an investigation into the feasibility of building ultra-large aperture visible/mid-IR space telescopes. A promising concept found by the study is a freely flying spherical primary mirror, twenty meters or more in diameter, located at the L1 or L2 Earth-Sun libration point. The primary would be passively cooled to 45 K. There would be no metering structure. Instead, using a combination of alignment and steering mirrors, reaction wheels, and microthrusters, the aspherical secondary mirror, active tertiary mirror, and focal plane instruments would be precisely stationed in the correct position above the primary. The primary advanced composition would be either a membrane or ultra-light segmented technology. Preliminary findings show that a 20-30 m telescope may be feasible for imaging in the 1-20 mu m regime.