the giant magellan telescope - 2006 mitchell symposium
TRANSCRIPT
Wendy Freedman Carnegie Observatories
Chair, GMT Board
Texas A&MMitchell Symposium
April 12, 2006
The Giant Magellan Telescope
GMT DesignAlt-az telescope structure
Seven 8.4-m primary mirrors
• 24.5-m diffraction equivalent
• 21.5-m equivalent aperture
GMT Institutions
• Carnegie Observatories• Harvard University
• Smithsonian Astrophysical Observatory
• Texas A&M University
• University of Texas, Austin• University of Arizona• University of Michigan• Massachusetts Institute of
Technology
• + …OTHERS TBD
The GMT
• Why this group of institutions?
More than 300 years of telescope building
experience within the consortium
Last telescope came in under budget
GMT Project Scientists Working Group
• Steve Shectman Carnegie Observatories
• Roger AngelU. Arizona
• Dan FabricantHarvard/Smithsonian CfA
• Phillip MacQueenU. Texas at Austin
• Rebecca BernsteinU. Michigan
• Paul SchechterMIT
• Matt JohnsCarnegie Observatories
•Charles JenkinsAustralia
Science Working Group• Warrick Couch
Australia
• Xiaohui FanArizona
• Karl GebhardtTexas
• Gary HillTexas
• John HuchraHarvard
• Scott KenyonSmithsonian
• Pat McCarthy (chair)Carnegie
• Michael MeyerArizona
• Alycia WeinbergerCarnegie/DTM
Telescope Structure & Optics
Height = 43 meters
Rotating: 961 tons
7 x 8.4m Primary mirror segments
+ 1 spare off-axis segment.
Windshake: 4.5Hz lowest structural modes
Mold assembly for GMT Mirror 1
Machine and install 1681 ceramic fiber boxes in silicon carbide tub.
Tops of boxes follow shape of aspheric surface; no two are identical.
Loading the Glass
Close furnace: melt and spin.
Inspect, weigh, and load 18 t of E6 borosilicate glass.
Casting First Off-Axis Segment: July 2006
First GMT off-axis segment
Heat to 1160˚C, spin at 4.9 rpm, hold 4 hours to allow glass to fill mold. Cool rapidly to 900˚C then slowly for 3 months, 2.4 K/day through annealing (530-450˚C).
Lift and washout
Tilted into vertical planeRear surface with floor tiles
attached
Segment with lifting fixture
Removal of floor tiles
New test tower at Mirror Lab
* Needed for 8.4 m
off-axis segments
* Long 36 m radius of curvature (LBT = 20 m)
* Requires diffraction limited 4 m folding spherical mirror at top
Segmented Adaptive Gregorian Secondary Mirror
Technology developed for MMT & LBT
7 Segments aligned with Primary mirror segments attached to a single reference body.
~672 actuators per segment
~4700 actuators total64 cm MMT AO secondary mirror
Baseline Adaptive Optics Modes
1) Ground Layer AO covering 8′ diameter field at the direct Gregorian focus (0.9-2.5 μm)
2) Laser Tomography AO providing high-Strehl, diffraction-limited correction across a 1′ to 4′diameter field at folded Gregorian focii on the instrument platform (0.9-2.5 μm)
3) Extreme Contrast AO optimized for the detection of planetary disks and young, hot planets with dedicated instruments on the instrument platform
First Generation Instrument ConceptsInstrument λ(μm) Resolution FOV Modes
Visible WF MOS
0.4 -1.0
500-5000 60-150�′ MOS, Imager
NIR MOS 0.9 -2.5
1500-5000 25-100�′ MOS/IFUImager
Visible Echelle
0.3 -1.0
20K -100K
20′′ Single Object Fiber feed
NIR Echelle 1 - 5 50K-150K 30′′ Single Object
MIR AO Imager
3 - 25 5-3000 2′ x 2′ Coronagraph Nulling int.
NIR AO Imager
1 - 2.5 5-5000 30′′ ``Wide-field’’ & high definition modes
GMT Instrument Platform (IP)
RotatorGLAO Guider
Folded portinstruments
Gregorianinstruments
capacity6.4 m Dia.7.6 m high
25 ton
Optical MOSNear-IR MOS
Mid-IR Spectrograh
EchelleAO imager
Site Testing
Northern Chile sites• GMT conducting tests at 4 LCO sites
• Coordinate/share data with other
projects
Test equipment• Differential Image Motion Monitors
(DIMM)
• Meteorological stations
• Multi-aperture Scintillation Sensor
(MASS)
• All-sky camera
• Precipitable Water Vapor
Magellan (Manqui) Campanas Pk.Alcaino Pk.
Ridge (Manquis)
Light PollutionCalculation of light pollution based on satellite imagery obtained in 1996-1997. Lowest contours indicate 1-10% increase over natural sky brightness
Source: http://www.lightpollution.it
Key Science Areas
• The First Stars and Galaxies
• Nature of Planets beyond our Solar System
• New Discoveries
www.gmto.org
Complementarity with JWST
JWST
GMT
JWST
GMT
10 AU
β Pic at 11μm
GMT has 4 times the spatial resolution…. and up to 100 times the spectral resolution
McCarthy
Origin and Evolution of Galaxies and Structure in the Universe
1. First light and reionization
2. Assembly of galaxies and clusters
3. Energetics of the IGM
4. Origin of the Hubble Sequence
CMB (WMAP image): seeds ofgalaxy and LSS formation
Sloan z > 6 quasar
Galaxy Assembly & First Light
With its wide field of view and enormous collecting
area GMT will:
• Probe star formation in the first billion years of cosmic time
• Gauge the formation of galaxies via the buildup of mass & heavy elements
• Explore the connection between galaxies and the intergalactic medium
He II 1640 emission-line Image in H-band
Numerical simulation
Star formation at z = 10 with GMT
Barton et al. 2005
Origins of Stars and Planets
1. What determines stellar, brown-dwarf and planet mass functions?
2. Environmental influence on planet formation process
3. Evolution from proto-planetary disks to planetary systems
Circumstellar debris disk
Radial velocity detection of planets
Large segments enable detection of extra-solar planets in reflected light
Physical Properties of Extra-Solar Planets
1. Physics of planetary atmospheres
2. Survival of “hot Jupiters”
3. What are the distributions of planetary temperature, albedo, mass, size?
Nulling interferometry at 10 μ m with Magellan
Model spectra of giant planets
GMT nullinginterferometry
GMT direct imaging
Planets and Their Formation
With its superb angular resolution & sensitivity
GMT will:
• Image known exoplanets in reflected light
• Discover young massive planets in nearby star forming regions
• Probe the structure of proto-planetary gas and debris disks
Can GMT carryout the NAS Decadal Survey Science case?
Yes! Some parts take ~30-50% longer, others may be faster than the nominal GSMT
What unique capabilities are offered by GMT?- Adaptive optics at the secondary- A unique PSF that is well suited to ExAO- Rapid instrument changes/TOO access- Wide-field GLAO - Wide-field spectroscopy without fibers
Schedule Milestones
Contract for 1st primary mirror segment 2004
Cast 1st segment 2005
Complete conceptual design (review) 2006
Complete Preliminary Design (reviews) 2008/9
Complete 1st segment 2008
Construction Phase Starts (assuming funding) 2009
First Light with 4 segments 2013
First science operation 2015
All 7 segments installed 2016
Toward Realizing the GMT
• Where are we now?
First primary mirror cast successfully in July
Conceptual Design completed
Conceptual Design Review of Project February
STRONG RECOMMENDATION TO PROCEED TO DDP!
Beginning Polishing/Testing phase of Mirror I.
Fundraising for Detailed Design in progress