Transcript Project Manager Presentation to the TMT Board

TMT: the next generation of
segmented mirror telescopes
Jerry Nelson, UCSC
GTC Inauguration Seminar
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2009 July 25
Outline
Project Introduction
Telescope overview
TMT key features
Major science goals
Science Instruments
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TMT Mauna Kea
Best highaltitude
seeing
4200 m
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ALMA and ELTs 2009
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3
Mauna Kea 13N site
Proposed Site Area
Prevailing wind
A
NORTH
Mauna Kea Science Preserve
Master Plan: Astronomy Precinct
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ALMA and ELTs 2009
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Project Introduction
Time line
–
–
–
–
2004
2009
2011
2018
project start, design development
preconstruction phase
start construction
complete, first light, start AO science
Partnership
–
–
–
–
–
–
UC
Caltech
Canada
Japan
NSF?
Other nations?
Cost
– 970M$ (2009$)
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What is TMT?
Thirty-meter
aperture
Filled,
segmented
primary
Elevation axis in
front of primary
Active and
adaptive optics
UV to thermal IR
Broad range of
instruments
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ALMA and ELTs 2009
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TMT features
14 - 200 times the
sensitivity of 8 m
telescopes (D2 - D4
gain)
3 - 5 times the
resolution of 8 m
telescopes and
JWST
20 arcmin field of
view
5 AO modes
Pointing in < 3 min
Instrument change in
< 10 min
Calotte enclosure
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Observatory Layout: Telescope
LGSF launch telescope
M2 support tripod
M2 structural hexapod
Tensional members
LGSF beam transfer
M2 hexagonal ring
M2 support columns
Elevation journal
Nasmyth
platform
Laser room
Azimuth cradle
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M1 cell
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Azimuth truss
TMT Optical Design:
Ritchey Chrétien
M1 Parameters
– ø30m, f/1, Hyperboloid
k = -1.000953
– Paraxial RoC = 60.0m
– Sag = 1.8m
– Asphericity = 29.3mm (entire M1)
M2 Parameters
– ø3.1m, ~f/1, Convex hyperboloid,
k = -1.31823
– Paraxial RoC = -6.228m
– Sag = ~650mm
– Aspheric departure: 850 mm
M3 Parameters
– Flat
– Elliptical, 2.5 X 3.5m
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Segment Size
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Nasmyth Configuration: First Decade
Instrument Suite
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Why build a 30-m telescope:
huge aperture advantage
Seeing-limited observations and observations of resolved sources
Sensitivity  D2 (~ 14  8m)
Background-limited AO observations of unresolved sources
Sensitivity  S2 D4 (~ 200  8m)
High-contrast AO observations of unresolved sources
2
S
Sensitivity  
D4 (~ 200  8m)
1 S
High-contrast ExAO observations of unresolved sources
Contrast  D2 (~ 14  8m)
Sensitivity  D6 (~ 3000  8m)
Sensitivity 1/ time required to reach a given s/n ratio
  throughput, S  Strehl ratio. D  aperture diameter
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Science Potential
Solar system detailed
studies
Direct imaging planets
around nearby stars
Stars and stellar evolution
Black holes and galaxies
Nearby galaxies
Distant galaxies and first
light
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Distant Galaxies – TMT+AO
Credit: M. Bolte
•TMT with AO angular resolution
100x better than seeing limited
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Primary Mirror Segments
TMT segmented mirror is an
evolution of the Keck mirror
36 segments, 1.8m, in each
Keck telescope
492 segments, 1.45m, in TMT
Polishing and segment module
fabrication must be “mass
produced” to cost and quality
TMT is working with industrial
partners to compete
production design, testing and
cost
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Segment Support
Assembly (SSA) Design
Seven Segment Assembly – Top
View
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Segment Support
Assembly (SSA) Design
Seven Segment
Assembly – Bottom
View
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Active Control Summary
Selected a = 0.72 m for segment size
Item
segment size
# segments
# edge sensors
# actuators
Keck
0.9m
36
168
108
TMT
0.72m
492
2772
1476
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Adaptive Optics
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Adaptive Optics
Adaptive optics seriously introduces the concept of high
speed, high bandwidth control
– Primary aim is to remove rapidly varying atmospheric turbulence
that causes image blur
– Secondary bi-product is ability to remove both slowly varying and
rapidly varying wavefront errors that are in the telescope
As currently envisioned and used, adaptive optics is only
practical in the near infrared, not the visible.
Adaptive optics is technologically challenging!
Result is diffraction-limited performance
– AO is revolutionary
– For TMT resolution of 0.005 arcsec 100x better than atmosphere
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Basic Elements of Adaptive Optics
Atmospheric turbulence…
introduces wavefront and image
quality degradations…
which can in principal be
compensated by a wavefront
corrector…
provided that they can be
measured with a wavefront
sensor…
observing a suitable reference
star
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starlight
Na laser beams (6 total)
Na Laser Tomography
and MCAO
35 arcsec
Na layer (~10 km)
“Meta-pupil” for a
+/-1 arc min FoV
90km
Light from 1 arcmin off axis
Turbulent atmosphere (~15 km)
30 m
DM conjugate to h ~ 10-12 km
DM conjugate to h= 0 km
TMT AO
NFIRAOS has two deformable mirrors- MCAO
– 64x64
– 73x73
NFIRAOS laser will produce 6 laser spots
– Illuminates Na layer, 90km up in the atmosphere
– 150 Watts Na power
– One central spot, 5 perimeter spots
Two arc minute field of view
Atmosphere is tomographically reconstructed, then
projected out in the direction of interest
Computationally intensive
– Solve 38000x7000 control problem at 800 Hz
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TMT AO Early Light Architecture
Narrow Field IR AO
System (NFIRAOS)
– MCAO LGS AO System
– Mounted on Nasmyth
Platform
– Feeds 3 science
instruments
NFIRAOS:
- 190nm RMS WFS
- 60x60 order system
- 2 DMs, 6 LGS, 3 TTF WFS
- 800Hz
Laser Guide Star Facility
(LGSF)
– Laser enclosure located
within telescope azimuth
structure
– Conventional optics for
beam transport
– Laser launch telescope
behind M2
LSE
AO Executive Software
(AOESW)
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NFIRAOS Interfaces with Nasmyth
Platform and Client Instruments
Future (third) Instrument
NFIRAOS Enclosure
Service Platform
Optics Bench and
Instrument Support
Structure
BTO Path
LGS WFS Optics
Nasmyth Platform
Interface
IRIS
Electronics Enclosure
Nasmyth Platform
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NFIRAOS Optics Benches
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Science instruments
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TMT First Decade Instrument/Capability Suite
Instrument
Near-IR DL Spectrometer &
Imager
(IRIS)
Spectral
Resolution
~4000
Wide-field Optical
Spectrometer
(WFOS)
1000-5000
Multi-slit near-DL near-IR
Spectrometer
(IRMS)
2000 - 5000
Mid-IR Echelle
Spectrometer & Imager
(MIRES)
5000 - 100000
ExAO I
(PFI)
50 - 300
High Resolution Optical
Spectrograph
(HROS)
30000 - 50000
MCAO imager
(WIRC)
5 - 100
Near-IR, DL Echelle
(NIRES)
5000 - 30000
Science Case
Assembly of galaxies at large redshift
Black holes/AGN/Galactic Center
Resolved stellar populations in crowded fields
Astrometry
IGM structure and composition 2<z<6
High-quality spectra of z>1.5 galaxies suitable for measuring stellar
pops, chemistry, energetics
Near-field cosmology
Near-IR spectroscopic diagnostics of the faintest objects
JWST follow-up
Physical structure and kinematics of protostellar envelopes
Physical diagnostics of circumstellar/protoplanetary disks: where and
when planets form during the accretion phase
Direct detection and spectroscopic characterization of extra-solar
planets
Stellar abundance studies throughout the Local Group
ISM abundances/kinematics, IGM characterization to z~6
Extra-solar planets!
Precision astrometry
Stellar populations to 10Mpc
Precision
radial velocities of M-stars and detection of low-mass planets
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IGM characterizations for z>5.5
TMT Early Light Instrument Suite
Instrument
Near-IR DL Spectrometer
& Imager
(IRIS)
Spectral
Resolution
≤4000
Science Case
Assembly of galaxies at large redshift
Black holes/AGN/Galactic Center
Resolved stellar populations in crowded fields
Astrometry
Wide-field Optical
Spectrometer
(WFOS)
300 - 5000
Multi-slit near-DL near-IR
Spectrometer
(IRMS)
2000 - 5000
Mid-IR Echelle
Spectrometer & Imager
(MIRES)
5000 100000
Physical structure and kinematics of protostellar envelopes
Physical diagnostics of circumstellar/protoplanetary disks: where
and when planets form during the accretion phase
ExAO I
(PFI)
50 - 300
Direct detection and spectroscopic characterization of extra-solar
planets
High Resolution Optical
Spectrograph
(HROS)
30000 50000
MCAO imager
(WIRC)
5 - 100
Near-IR, DL Echelle
5000 - 30000
IGM structure and composition 2<z<6
High-quality spectra of z>1.5 galaxies suitable for measuring
stellar pops, chemistry, energetics through peak epoch of gal form.
Near-IR spectroscopic diagnostics of the faintest objects
JWST followup
Stellar abundance studies throughout the Local Group
ISM abundances/kinematics, IGM characterization to z~6
Extra-solar planets!
Galactic center astrometry
Stellar populations to 10Mpc
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Precision radial velocities of M-stars and detection of low-mass
planets
IRIS - Infrared imaging spectrometer
imager filter
wheels
2’
IRIS dewar
(at 77k)
WFS
IFUs
Grating
imager
Common
spectrograph
and camera
for both IFUs
F/15 AO Focus
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IRMS - Infrared multislit spectrometer
0.8 - 2.5 um cryogenic
multi-slit spectrometer
2.3 arcmin field of view
0.06 arcsec sampling
46 moveable slits 2.4” long
Covers entire Y, J, H or K
band at R = 4660
WFOS - Wide-field optical spectrograph
0.31 - 1.1 um wavelength
range
Observe up to 1500 objects
over a 40.5 sq. arcmin FOV
Spectral resolution 300 - 7500
Reflecting gratings / prism
cross-dispersion, and fixed
dichroic beamsplitter at 550nm
“Echellette” design provides up
to 5 orders
Full wavelength coverage,
even at highest resolution, for
“discovery science”
Low resolution mode (single
order) for maximum multiplex
advantage
Summary
TMT will be a 30-m telescope with AO capabilities from
the start
– ~ 190 nm rms wavefront error over 10 arcsec
– First light 2018
Very large and exciting science case
8 instruments planned for the first decade
3 instruments planned for first light
– IRIS (an AO NIR integral field spectrograph and imager)
– IRMS (an AO NIR multi object spectrometer (46 slits)
– WFOS (a seeing-limited multiobject spectrometer with R<8000,
and ~ 50 arcmin2coverage)
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TMT Foundation Documents
www.tmt.org/foundation-docs/index.html
Detailed Science Case 2007
Observatory Requirements Document
Observatory Architecture Document
Operations Concept Document
TMT Construction Proposal
– Currently in use for funding proposals
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