Conceptual Design for a 16-m Segmented UVOIR Space Telescope

16-m ATLAST Conceptual Design Telescope Requirements As indicated by the title of this poster, the three fundamental requirements for this telescope are a 16-m entrance pupil diameter, a primary mirror consisting of segments, and a bandwidth from approximately 120 nm (Lyman α) to 2 μm. The wavefront error (WFE) requirement, as specified by the science team, is diffraction-limited performance (λ/14) at 500 nm. Of the allowed 36 nm rms WFE, we have allocated 25 nm (λ/20) to the design as a requirement with a goal of 20 nm (λ/25). This allocation is based on an error budget for a generic large aperture, segmented telescope with segment rigid body and figure control. It is recognized that the telescope will also need pointing control. However, the level of pointing stability is likely to vary between the instruments. For example, the visible imager will require submilliarcsecond pointing stability. We have opted to include pointing sensors as part of the instrument suite but let the individual instruments implement their own pointing mechanisms.