Presentation #206.11 in the session New Mission Concepts — iPoster Session.
Astro2020 recommended that the next IR/O/UV Great Observatory be unobscured and at least 6-m in aperture. Both segmented and monolithic telescopes are to be considered. HabEx has addressed a 4m unobscured monolithic mirror and LUVOIR B an unobscured 8m segmented mirror. While the James Webb Space Telescope, optimized at 2-micron wavelength, was recently launched with 18 hexagonal mirror segments, is this the best solution for UV? Especially, is this optimum for coronagraphy where a contrast ratio of at least 10 billion-to-one is needed? While some initial reactions suggested the opinion that the infrastructure is not present for a 6-m monolith, is it that far away? We will discuss first what it would take at SCHOTT to implement such a monolithic mirror from a single casting of ZERODUR. We will summarize the technology already demonstrated at SCHOTT for making even larger mirror blanks for the Very Large Telescopes via spin casting, and address in a preliminary sense the augmentations/investments needed for full-up lightweighting and generating the aspheric form. Furthermore, we will summarize initial feedback from optical polishing houses and coating houses suggesting that to fully implement the 6m form prescribed by Astro2020 as an extremely homogeneous and thermally stable monolith, free of bonding or fusing belongs in trade space.