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Future Giant Telescope (FGT) Projects and Their Technological Challenges: 

IAU Joint Discussion 8 July 17, 2003 Larry Stepp Future Giant Telescope (FGT) Projects and Their Technological Challenges

Outline: 

Outline Introduction: how FGTs will advance beyond current-generation telescopes A brief history of FGTs Current concepts for FGTs Technology challenges common to all

Current-Generation Telescopes: 

Current-Generation Telescopes 8- to 10-meter telescopes have achieved better performance at lower relative cost by reducing the size and mass of telescope & enclosure Improvements in polishing and testing techniques have enabled faster primary mirrors Active optics has achieved tighter alignment tolerances and enabled mirrors to be made lightweight Faster primaries, lighter mirrors, alt-azimuth mounts & FEA have resulted in smaller, stiffer telescope structures Smaller, stiffer structures have allowed enclosures to be smaller and better ventilated, improving local seeing As a result, sub-half-arc-second images are becoming commonplace

Mayall  Keck: 

Mayall  Keck 350 tonnes 270 tonnes Cost in 1973: $10.6 M Adjusted to 1992: $33.7 M Projected cost of 10m in 1992: $400 M Actual cost of Keck 10m telescope in 1992: $110 M

Future Giant Telescopes: 

Future Giant Telescopes FGTs will continue the trends of the current generation Faster primary focal ratios Relatively lighter structures And they will advance beyond the Current Generation Integral adaptive optics systems Smart structures This will enable FGTs to have: An order of magnitude more light-gathering power Better image quality and resolution Diffraction-limited at  > 1 micron However, significant technological challenges must be solved to make this possible

A Brief History of Future Giant TelescopesThe Kitt Peak Next Generation Telescope: 

A Brief History of Future Giant Telescopes The Kitt Peak Next Generation Telescope 25-m telescope Segmented f/1 primary Radio-telescope style mount Concept from 1977

A Brief History of Future Giant TelescopesThe National New Technology Telescope (NNTT): 

A Brief History of Future Giant Telescopes The National New Technology Telescope (NNTT) 16-m telescope MMT-type Four 8-m f/1.8 primary mirrors Concept from 1986

A Brief History of Future Giant TelescopesMore Concepts Were Advanced in the Early 1990s: 

A Brief History of Future Giant Telescopes More Concepts Were Advanced in the Early 1990s J. R. P. Angel, Filled Aperture Telescopes in the Next Millennium, SPIE 1236, 1990. A. Ardeberg, T. Andersen, B. Lindberg, M. Owner-Petersen, T. Korhonen, P. Søndergård, Breaking the 8m Barrier - One Approach for a 25m Class Optical Telescope, ESO Conf. and Workshop Proc. No. 42, 1992. M. Mountain, What is beyond the current generation of ground-based 8-m to 10-m class telescopes and the VLT-I?, SPIE 2871, 1996. F. N. Bash, T. A. Sebring, F. B. Ray, L. W. Ramsey, The extremely large telescope: A twenty-five meter aperture for the twenty-first century, SPIE 2871, 1996. V. V. Sytchev, V. B. Kasperski, S. M. Stroganova, V. I. Travush, On conceptual design options of a large optical telescope of 10...25 metre class, SPIE 2871, 1996.

Current Concepts for FGTsLarge Aperture Telescope (LAT): 

Current Concepts for FGTs Large Aperture Telescope (LAT) LAT Consortium Cornell Chicago Illinois Northwestern Site: high Atacama desert or Antarctica Design concept for LAT From a presentation by Ed Kibblewhite

Large Aperture Telescope (LAT): 

Large Aperture Telescope (LAT) Interesting Features of Concept: Adaptive primary mirror Design shown would have 36-m primary with 28-m adaptive central zone Science goals emphasize IR and sub-millimeter wavelengths Low PWV sites provide logistical challenges

Large Aperture Telescope (LAT): 

Large Aperture Telescope (LAT) Design Parameters Optical design: TBD Primary mirror diameter 20-m to 36-m Primary mirror focal ratio TBD (~ f/1) Secondary mirror diameter TBD Final focal ratio TBD Field of View: 5’ - 10’ Instrument locations: Cassegrain Elevation axis location: Below primary mirror

Large Aperture Telescope (LAT): 

Large Aperture Telescope (LAT) Key Technical Challenges Cost-effective fabrication of lightweight, off-axis aspheric segments Structure needs high damping Momentum compensation for adaptive segments Efficient segment co-phasing systems Laser guidestar beacons Site survey studies of CN2 profile More information is available at: http://astrosun.tn.cornell.edu/atacama/atacama.html

Magellan 20: 

Magellan 20 Partner organizations include: Carnegie Harvard Smithsonian MIT Arizona Michigan Site: Las Campanas, Chile Design Concept for Magellan 20 From a presentation by Roger Angel

Magellan 20: 

Magellan 20 Interesting Features of Concept: Primary consists of seven 8.4-m mirrors Segmented, adaptive secondary Ground-conjugate adaptive optics Allows later incorporation into a 20-20 interferometer

Magellan 20: 

Magellan 20 Design Parameters Optical design: Aplanatic Gregorian Primary mirror diameter 26-m (22-m equiv.) Primary mirror focal ratio f/0.7 Secondary mirror diameter 2.5-m Final focal ratio f/10 Field of View: 12’ - 20’ Instrument locations: Nasmyth Nasmyth (vertical) Cassegrain Elevation axis location: Below primary mirror

Magellan 20: 

Magellan 20 Key Technical Challenges Fabrication & testing of highly-aspheric 8.4-m off-axis segments Segmented adaptive secondary mirror Laser guidestar beacons Multi-conjugate adaptive optics More information is available at: http://helios.astro.lsa.umich.edu/magellan/intro/science_case_march16.htm

High Dynamic Range Telescope: 

High Dynamic Range Telescope Design developed by: Univ. of Hawai’i Site: Mauna Kea, Hawai'i (replace the CFHT) Design concept for HDRT From a paper by Kuhn et al

High Dynamic Range Telescope: 

High Dynamic Range Telescope Interesting Features of Concept: Rapidly switchable narrow-field & wide-field modes Segmented secondary mirrors Concept for bi-parting enclosure Adaptive structure

High Dynamic Range Telescope: 

High Dynamic Range Telescope Design Parameters Optical design: Gregorian (NF) 3-mirror anastigmat (WF) Primary mirror diameter 22-m (16-m equiv.) Primary mirror focal ratio f/1 Secondary mirror diameter six @ 0.14-m (NF) six @ 2.3-m (WF) Tertiary mirror diameter 7-m Final focal ratio f/15 (NF); f/1.9 (WF) Field of View: 3” (NF); 2 degrees (WF) Instrument locations: Central Elevation axis location: Above primary mirror

High Dynamic Range Telescope: 

High Dynamic Range Telescope Key Technical Challenges Fabrication of & testing of 6.5-m off-axis aspheric primary mirror segments Fabrication & testing of 2.3-m off-axis secondary mirror segments Adaptive telescope structure Laser guidestar beacons More information is available at: http://www.ifa.hawaii.edu/users/kuhn/hdrt.html

Large Petal Telescope: 

Large Petal Telescope Design developed by: Obs. Astron. Marseille-Provence Obs. Astron. de Paris Site: Mauna Kea, Hawai'i (replace the CFHT) Design concept for LPT From a paper by Burgarella et al

Large Petal Telescope: 

Large Petal Telescope Interesting Features of Concept: Primary consists of six or eight 8-m sector-shaped, meniscus segments 3-mirror or 4-mirror optical design Simultaneous use of 6-8 instruments Adaptive telescope structure

Large Petal Telescope: 

Large Petal Telescope Design Parameters Optical design: 3- or 4-mirror anastigmat Primary mirror diameter 20-m + Primary mirror focal ratio f/1 Secondary mirror diameter 2.5-m to 5-m Final focal ratio f/5 to f/7.5 Field of View: 1 degree Instrument locations: Cassegrain Elevation axis location: Below primary mirror

Large Petal Telescope: 

Large Petal Telescope Key Technical Challenges Fabrication & testing of 8-m off-axis aspheric primary mirror segments Fabrication & testing of secondary mirror Adaptive telescope structure Multi-conjugate adaptive optics Laser guidestar beacons More information is available at: http://www.astrsp-mrs.fr/denis/ngcfht/ngcfht.html

Very Large Optical Telescope (VLOT): 

Very Large Optical Telescope (VLOT) Design developed by: HIA AMEC Site: Mauna Kea, Hawai'i (replace the CFHT) Design Concept for VLOT AMEC Dynamic Structures

Very Large Optical Telescope (VLOT): 

Very Large Optical Telescope (VLOT) Interesting Features of Concept: Considering concept with 8-m diameter central mirror surrounded by sector-shaped smaller segments Calotte dome concept

Very Large Optical Telescope (VLOT): 

Very Large Optical Telescope (VLOT) Design Parameters Optical design: Ritchey-Chrétien Primary mirror diameter 20-m Primary mirror focal ratio f/1 Secondary mirror diameter 2.5-m Final focal ratio f/15 Field of View: 20’ Instrument locations: Nasmyth (vertical) Elevation axis location: Below primary mirror

Very Large Optical Telescope (VLOT): 

Very Large Optical Telescope (VLOT) Key Technical Challenges Cost-effective fabrication of lightweight, off-axis aspheric segments Fabrication & testing of secondary mirror Laser guidestar beacons Multi-conjugate adaptive optics Laser guidestar beacons More information is available at: http://www.hia-iha.nrc-cnrc.gc.ca/VLOT/index.html.

California Extremely Large Telescope (CELT): 

California Extremely Large Telescope (CELT) CELT Partnership Caltech Univ. of California Site: TBD (Mauna Kea or northern Chile or Mexico) Design concept for CELT From the CELT Greenbook

California Extremely Large Telescope (CELT): 

Interesting Features of Concept: Scaled up Keck design with 1080 segments arranged in 91 rafts Large Nasmyth platforms California Extremely Large Telescope (CELT)

California Extremely Large Telescope (CELT): 

Design Parameters Optical design: Ritchey-Chrétien Primary mirror diameter 30-m Primary mirror focal ratio f/1.5 Secondary mirror diameter 3.96-m Tertiary mirror major axis 4.38-m Final focal ratio f/15 Field of View: 20” Instrument locations: Nasmyth Elevation axis location: Above primary mirror California Extremely Large Telescope (CELT)

California Extremely Large Telescope (CELT): 

California Extremely Large Telescope (CELT) Key Technical Challenges Cost-effective fabrication of 1080 off-axis aspheric primary mirror segments Fabrication & testing of secondary mirror Fast tip-tilt-piston of secondary and tertiary mirrors Efficient segment co-phasing systems Laser guidestar beacons Multi-conjugate adaptive optics More information is available at: http://celt.ucolick.org/

Giant Segmented Mirror Telescope: 

Giant Segmented Mirror Telescope Design by AURA New Initiatives Office NOAO Gemini Site: TBD (Mauna Kea or northern Chile or Mexico) Design Concept for GSMT From animation by Rick Robles

Giant Segmented Mirror Telescope: 

Giant Segmented Mirror Telescope Interesting Features of Concept: Prime focus instrument Aperture stop at secondary Adaptive secondary

Giant Segmented Mirror Telescope: 

Giant Segmented Mirror Telescope Design Parameters Optical design: Cassegrain (or R-C) Primary mirror diameter 32-m (30-m equiv.) Primary mirror focal ratio f/1 Secondary mirror diameter 2-m Final focal ratio f/18.75 Field of View: 20” Instrument locations: Prime focus Nasmyth Cassegrain (moving & fixed) Elevation axis location: Below primary mirror

Giant Segmented Mirror Telescope: 

Giant Segmented Mirror Telescope Key Technical Challenges Cost-effective fabrication of 618 off-axis aspheric primary mirror segments Efficient segment co-phasing systems Adaptive secondary mirror Laser guidestar beacons Multi-conjugate adaptive optics Adaptive telescope structure More information is available at: www.aura-nio.noao.edu/

Euro50: 

Euro50 Euro50 partners Lund University Inst. de Astrofisica de Canarias Dept. of Physics, Galway, Ireland Tuorla Observatory Optical Science Lab. National Physical Lab. Site: La Palma Design Concept for Euro50 From Euro50 web site

Euro50: 

Euro50 Interesting Features of Concept: Adaptive secondary with composite face sheet F/5 focal reducer for seeing-limited observing

Euro50: 

Euro50 Design Parameters Optical design: Gregorian Primary mirror diameter 50-m Primary mirror focal ratio f/0.85 Secondary mirror diameter 4-m Final focal ratio f/13; also: f/5; f/16; f/20 Field of View: 4’ Instrument locations: Nasmyth Folded Cassegrain Elevation axis location: Below primary mirror

Euro50: 

Euro50 Key Technical Challenges Cost-effective fabrication of 618 off-axis aspheric primary mirror segments Efficient segment co-phasing systems Adaptive secondary mirror Laser guidestar beacons Multi-conjugate adaptive optics More information is available at: http://www.astro.lu.se/~torben/euro50/

Overwhelming Large Telescope (OWL): 

Overwhelming Large Telescope (OWL) Design by European Southern Observatory Site: TBD Design Concept for OWL From OWL web site

Overwhelming Large Telescope (OWL): 

Overwhelming Large Telescope (OWL) Interesting Features of Concept: Spherical primary mirror Flat segmented secondary mirror Three aspheric mirrors Elevation assembly recessed into ground Mount tied to ground by multiple drive bogies

Overwhelming Large Telescope (OWL): 

Overwhelming Large Telescope (OWL) Design Parameters Optical design: Six-mirror design Primary mirror (M1) diameter 100-m Primary mirror focal ratio f/1.42 Secondary mirror (M2) diameter 26-m M3 diameter 8.1-m M4 diameter 8.2-m M5 diameter 3.5-m Final focal ratio f/7.5 Field of View: 10’ Instrument locations: Central Elevation axis location: Above primary mirror

Overwhelming Large Telescope (OWL): 

Overwhelming Large Telescope (OWL) Key Technical Challenges Fabrication of large numbers of lightweight segments Active structure to move corrector Efficient segment co-phasing systems Multi-conjugate adaptive optics 2.4-m adaptive flat mirror 3.5-m adaptive curved mirror More information is available at: http://www.eso.org/projects/owl/

Required Technology Developments:Telescope & Optics : 

Required Technology Developments: Telescope & Optics

Required Technology Developments:Telescope & Optics : 

Required Technology Developments: Telescope & Optics

Required Technology Developments:Adaptive Optics: 

Required Technology Developments: Adaptive Optics

Required Technology Developments:Adaptive Optics: 

Required Technology Developments: Adaptive Optics

Required Technology Developments:Adaptive Optics: 

Required Technology Developments: Adaptive Optics

Required Technology Developments:Adaptive Optics: 

Required Technology Developments: Adaptive Optics

Required Technology Developments:Instruments: 

Required Technology Developments: Instruments Affordable large near-IR detectors Affordable large mid-IR detectors Advanced image slicers for IFUs Fiber positioners MOEMS slit masks for multi-object spectroscopy Large-format volume-phase holographic gratings Large-format immersed silicon gratings Large lenses & filters

Call For International Cooperation: 

Call For International Cooperation Our needs are so similar and our resources are limited, close cooperation is essential: Joint ventures where sensible Coordination to ensure studies are complementary Open sharing of information as much as possible