Mega Telescopes of the 21 st Century Evolution in the Ground-Space Synergy Dr. Marc Postman (STScI) & Richard Ellis (Caltech) James Webb Space Telescope (6.5m telescope) Concept for 30m Ground-based Telescope (TMT)

GalileoNewton Keck Primary Telescope Aperture vs Time TMT

How to win at Astronomy Galileo Sensitivity Improvement over the Eye Year of observations Telescopes alone Photographic & electronic detection Huygens eyepiece Slow f ratios Short’s 21.5” Herschell’s 48” Rosse’s 72” Photography Mount Wilson 100”Mount Palomar 200”Soviet 6-m Adapted from Cosmic Discovery, M. Harwit Slide courtesy of J. Gardner 10 CCDs HST JWST Big Telescopes with Sensitive Detectors in Space (but also on the ground)

8m Ground (0.4 arcsec) HST (0.1 arcsec) D.L. 30m Telescope (0.008 arcsec) How a galaxy at a redshift of ~1 (7 billion l.y. away) would appear …

NASA’s Great Observatories~$2.5B investment in 8-10m telescopes Synergistic attributes: Space: unique wavelengths, angular resolution limited primarily by the size of telescope, very much reduced IR background, single telescope can see the entire sky Ground: spectroscopy of very faint objects, panoramic fields, upgradable technologies

Large Ground-based Telescope Design Concepts Giant Magellan Telescope Seven 8.4m monolithic mirrors Total Effective Diameter: ~22m Giant Segmented Mirror Telescope (aka TMT) m segments Total Effective Diameter: 30m Shown to same relative scale

Adaptive Optics: “Eye Glasses” for Ground-based Telescopes Credit: Clip from European Southern Observatory Press Release Computer driven actuators alter the shape of a “Deformable” Mirror to compensate for the atmospheric distortions. The mirror is a small mirror placed near the focal point of the telescope and thus the distortions can be made rapidly and across many points.

Performance of Keck NGS AO System: Miranda+UranusNeptuneTitan Courtesy: Wizinowich & Keck AO team Same objects with Hubble:

But AO has its Limits… Space provides unique access to UV, x-rays Space provides very stable environment where image resolution is limited primarily by the size of the telescope. NIR sky background vastly lower in space Sky from Mauna Kea Sky from JWST

The James Webb Space Telescope JWST will beJWST will be –36x faster than HST –2000x faster than Spitzer JWST will have an overwhelming advantage for imaging at wavelengths > 2 microns and for spectroscopy at wavelengths longer than 3 micronsJWST will have an overwhelming advantage for imaging at wavelengths > 2 microns and for spectroscopy at wavelengths longer than 3 microns TMT will rule below 2 microns but...TMT will rule below 2 microns but... Together, JWST and TMT should continue the type of scientific breakthroughs made possible by HST and the current 8-10m ground-based telescopes

Impact of Evolving Synergy High Angular resolution is increasingly a science-driven requirement for astronomy Extremely Large Telescopes + next generation AO will redefine the capabilities Unassailable advantages of space (in UVOIR range) - panoramic imaging (AO always ineffective) - optical and UV: very significant opportunities JWST does not provide these capabilities But we can we imagine even larger ground-based or space-based telescopes?

Proposed layout of OWL 100m telescope and enclosure Keck Obs. (to scale) Keck Obs. (to scale)

Technology Challenge 2.4m ~ $4B (FY07) 6.5m ~ $4B (FY07) m ~ $4B (FY07)