Mega Telescopes of the 21st Century

Evolution in the Ground-Space Synergy

Dr. Marc Postman (STScI) & Richard Ellis (Caltech)

Mega Telescopes of the 21st 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)

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Primary Telescope Aperture vs Time

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How to win at Astronomy

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Adapted from Cosmic Discovery, M. Harwit

Slide courtesy of J. Gardner

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8m Ground (0.4 arcsec)8m Ground (0.4 arcsec)

HST (0.1 arcsec)HST (0.1 arcsec)

D.L. 30m Telescope (0.008 arcsec)D.L. 30m Telescope (0.008 arcsec)

How a galaxy at a redshift of ~1 (7 billion l.y. away) would appear …

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

Large Ground-based Telescope Design Concepts

Giant Magellan Telescope Seven 8.4m monolithic mirrorsTotal Effective Diameter: ~22m

Giant Segmented Mirror Telescope (aka TMT)738 1.2m segments

Total Effective Diameter: 30m

Shown to same relative scale

Adaptive Optics: “Eye Glasses” for Ground-based Telescopes

Adaptive Optics: “Eye Glasses” for Ground-based Telescopes

QuickTime™ and aH.263 decompressor

are needed to see this picture.

Credit: Clip from European Southern Observatory Press Release

Computer driven actuators alter the shape of a Computer driven actuators alter the shape of a “Deformable” Mirror to compensate for the “Deformable” Mirror to compensate for the atmospheric distortions. The mirror is a small atmospheric distortions. The mirror is a small mirror placed near the focal point of the mirror placed near the focal point of the telescope and thus the distortions can be made telescope and thus the distortions can be made rapidly and across many points.rapidly and across many points.

Performance of Keck NGS AO System:Miranda+Uranus Neptune Titan

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 TelescopeThe James Webb Space Telescope

• JWST will beJWST will be– 36x faster than HST36x faster than HST– 2000x faster than Spitzer 2000x faster than Spitzer

• JWST will have an JWST will have an overwhelming advantage overwhelming advantage for imaging at for imaging at wavelengths > 2 microns wavelengths > 2 microns and for spectroscopy at and for spectroscopy at wavelengths longer than wavelengths longer than 3 microns3 microns

• TMT will rule below 2 TMT will rule below 2 microns but ...microns but ...

Together, JWST and TMT should continue the type of scientific breakthroughs Together, JWST and TMT should continue the type of scientific breakthroughs made possible by HST and the current 8-10m ground-based telescopesmade 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)

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18m ~ $4B (FY07)