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
TMTTMT
How to win at Astronomy
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Adapted from Cosmic Discovery, M. Harwit
Slide courtesy of J. Gardner
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Big Telescope
s with Sensitive Detectors in Space
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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)