The Thirty Meter Telescope Jerry Nelson, UCSC 2005 December 8

JEN TMT status2 Contents Lessons of History and Predicting the Future Scientific Potential of TMT TMT Organization TMT conceptual design –Overall structure –Optical design –Primary mirror –Segment geometry –Segment fabrication –Active control –Enclosure Adaptive Optics Status

2005 December 8JEN TMT status4 Predicting the future Proposed Future Ground Based Telescopes –California Extremely Large Telescope (CELT) 30 m –20/20 (University of Arizona study) 30 m equivalent –Giant Magellan Telescope20m –Euro 50 (Lund University study) 50m –OWL (ESO study) 100m (<60m) –TMT (merger of CELT, GSMT, VLOT)30m Major Issues (mainly cost) –mass production of optics –active control –adaptive optics –structural issues –enclosure/ weather protection

2005 December 8JEN TMT status5 Science Potential for TMT Increased angular resolution –With AO can reach arc second resolution (100x improvement) –Study morphological details of most distant galaxies (cosmology) –Study details for star and planet formation –Study stellar evolution in globular clusters –Quasars and Active Galactic Nuclei (black holes) –Solar system objects Increased light gathering power –With TMT can collect 9x the energy from an object (over Keck) –Spectroscopy of most distant objects known –Planet searches and their study

2005 December 8JEN TMT status6 Scientific Potential Seeing limited observations – µm –Scale 2.18 mm/arc second (f/15) –Wide field of view available: 20 arcminutes Diffraction limited observations –1-25µm, mainly 1-2.5µm –Thermal IR possible, but not most important –At 1 µm angular resolution of 7 mas –Resolution element size: 15µm (at f/15, 1 µm wavelength) –Large field of view: 1 arc minute at 1 µm with multi conjugate AO

2005 December 8JEN TMT status7 Thirty Meter Telescope TMT is a project to build a 30-m telescope UC and Caltech are partners (CELT) + Canada + AURA Design and prototyping money is ~ here $70M total needed –$35 UC+Caltech (CELT) from Moore Foundation –Canada contributes $17.5M –AURA should contribute $17.5M (highly uncertain) Site is unknown (several candidates being studied) Project manager (Gary Sanders from LIGO) Project scientist (J. Nelson) Project office in Pasadena

2005 December 8JEN TMT status8 TMT Project Organization

2005 December 8JEN TMT status9 Original Point Designs GSMTCELTVLOT cnrc.gc.ca/VLOT/index.html

2005 December 8JEN TMT status10 Site Selection We have a team of research scientists studying potential sites for TMT Sites are being studied in Chile, San Pedro Martir (Baja) and Mauna Kea, HI Measurements include –Weather (cloudiness, wind, temperature, humidity, dust) –Atmospheric seeing (total seeing with DIMM’s, profile with MASS and with SODAR’s) Expect to select qualified sites in 2007 Hope for competition between qualified sites to host TMT

2005 December 8JEN TMT status11 TMT Optical Design Primary is 30m in diameter –738 segments, 1.2 m dia each –Shape actively controlled (segment piston, tip, tilt) –f/1.0 ellipsoid Final: f/15 Aplantic Gregorian –Secondary 3.5m in diameter (concave) –20 arc minute field of view with 0.5 arc second images –1 arc minute FOV with arc second images (design) –Science from 1° to 65° zenith angle Instruments at Nasmyth platforms –Articulated tertiary allows direct feed to multiple instruments with no additional optics (3 mirrors total) –2 platforms: 15x30 m –Possible lower or upper platforms

33.32m 3.32m 3.58m 3.5m 30m 20m TMT Optics

2005 December 8JEN TMT status13 30m Primary Mirror Concept

TMT Keck

2005 December 8JEN TMT status15 TMT Reference Design

60m 20m 32m 40m 2m 34m

2005 December 8JEN TMT status17 Segment Fabrication Segments are off axis sections of ellipse –Requirements: ~ 20 nm rms surface (better than Keck) –~ 90 µm deviation from sphere (Keck was ~ 100µm) Fabrication study contracts (3) in place: Sagem, Zygo, ITT- Tinsley –Stressed mirror polishing (oap to sphere) favored by all –Planetary polishing to increase efficiency (simultaneous polishing of multiple mirrors) –Low expansion material will be used –Final figure corrections with ion figuring likely Segment warping harnesses (WH) –Will remove low spatial frequency segment errors caused by testing errors, polishing errors, support errors, thermal errors, alignment errors –Will ease tolerances (and costs) of fabrication, etc

2005 December 8JEN TMT status18 Planetary polishing to produce 800 segments

2005 December 8JEN TMT status19

Full stressing fixture

Planetary Stressed Mirror Polishing

2005 December 8JEN TMT status22 Passive segment support Design work contracted to Hytec (Los Alamos) Basic requirements –Support segments against gravity and thermal disturbances –Maintain desired surface figure to ~ 5 nm rms –Accurately maintain segment in desired location –Provide interface between actuators and mirror –Provide stiff (50Hz natural frequency) support –Allow for handling of segments for coating and recoating –Allow for warping harnesses to adjust low order shape of segment –Inexpensive to design, build, install, adjust –Zero maintenance for life of telescope

2005 December 8JEN TMT status23 SSA Concept

2005 December 8JEN TMT status24 Active Control Active control algorithm (details by G. Chanan) –Same idea as Keck: edge sensors, actuators, least squares fitting –Error propagation calculated to be acceptable: ~ 10x sensor noise Edge sensors –Relative to Keck, want lower cost, avoid mechanical interlace –New sensor design is still capacitive, but ~ on edges of segment –Design by Mast and LBL engineering Actuators –Relative to Keck, want lower cost, higher stroke –Keck actuators used roller screw/hydro reducer (position actuator) –TMT contract with Marjan to design and build a voice coil based force actuator. This should have 4x stroke and be ~ 1/4 Keck cost

2005 December 8JEN TMT status25 Active Control Summary Selected a = 0.6 m for segment size ItemKeckTMT segment size0.9m0.6m # segments36738 # edge sensors # actuators

2005 December 8JEN TMT status26 Actuator (piston) Sensor (measures height difference) Principle of active control with edge sensors s P1P1P1P1 P2P2P2P2 P3P3P3P3 P5P5P5P5 P4P4P4P4 P6P6P6P6 P9P9P9P9 P7P7P7P7 P8P8P8P8 Sensor signal depends only on motion of two neighbor segments a are constant coefficients that depend only on geometry

2005 December 8JEN TMT status27 Mirror Segment 7.5 cm Sensor Paddle Sensor Body Sensor Mount Conducting Surfaces 2 mm L R = 35 m Keck Sensor Geometry

2005 December 8JEN TMT status28 title Proposed TMT Sensor Geometry Non-Interlocking Sensors

2005 December 8JEN TMT status29 Concept of segment support Segment Actuator Reference Frame Mirror Cell Truss Actuator Whiffle Tree Moving Frame

2005 December 8JEN TMT status31 Enclosures Design options under study (from NIO)

2005 December 8JEN TMT status32 Adaptive Optics for TMT First generation –NFIRAOS Near IR AO system with rms wavefront error ~ 190 nm. Generates Strehl ratio ~ 0.7 at 2µm Hoping to upgrade to rms wavefront ~ 130 nm sometime after first light Large sky coverage (>50%) Na laser guide stars do atmospheric tomography Small field of view: 10”-1’ Remember diffraction limit at 1µm is arcsec –MIRAO 5-25µm diffraction limited system

2005 December 8JEN TMT status33 Science Instruments Seeing limited instruments (studies underway) –HROS: high resolution optical spectrometer- ~ HIRES –WFOS: wide field optical spectrograph ~ LRIS, DEIMOS multi object spectrometer, Fov ~ 20 arc min Diffraction limited instruments (studies underway) –IRIS –MIRES –NIRES –WIRC –MOAO

2005 December 8JEN TMT status34 Construction Phase Approval to start ($$ available)Jan 2008 Primary mirror detail design reviewApr 2008 Site Development FDRApr 2008 Complete enclosureFeb 2012 Complete telescope installationOct 2012 Begin segment installationAug 2012 First light with 1/4 segmentsJul 2013 All segments installed, phasedApr 2014 Begin TMT scienceJan 2015

2005 December 8JEN TMT status35 Development phase Conceptual design reviewMay 2006 Cost reviewSept 2006

2005 December 8JEN TMT status36 TMT AO Development Program DDP program addresses TMT AO architecture, design and technology development Key technologies and demonstrations – MEMS –Lasers –Infrared tip-tilt wavefront sensing –Open loop control –Tomography –Wavefront sensor –Adaptive secondary technology AO development addressed by an $11.7M DDP plan

2005 December 8JEN TMT status37 end

2005 December 8JEN TMT status38 TMT Experience with Adaptive Optics UC Lick Palomar Keck CFHT Gemini

2005 December 8JEN TMT status39 40 x 40 arcsecond mosaic, color- composite NIRC2 image (at ~2.2 um) of the Galactic Center using Keck Laser Ghez (UCLA) & collaborators Adaptive Optics has come of age! Gemini Hokupa’a/QUIRC image of Galactic Center. Expanded view shows IRS 13E & W in K p

2005 December 8JEN TMT status40 NGS / LGS Comparison NGS-AO best June 2004 (4 nights) 46 best x (0.50x120) SR=0.34, FWHM=92 mas LGS-AO 26 July x (0.25x120) SR=0.75, FWHM=82 mas GC

2005 December 8JEN TMT status41 Courtesy: L. Sromovsky Keck AO Imaging of Uranus

2005 December 8JEN TMT status42 Representative Construction Budget Construction Phase ($800M)*Possible NSF contribution –2008 $50M$12-25M –2009 $100M$25-50M –2010$160M$40-80M –2011$180M$45-90M –2012$140M$35-70M –2013 $100M$25-50M –2014 $70M$18-35M *Current range of estimates $600M-$800M

2005 December 8JEN TMT status43

2005 December 8JEN TMT status44 CELT AO Approach We are exploring a staged AO implementation, to match the evolving technology Each level change has a smaller wavefront error Each level change requires more and better deformable mirrors Each level change requires more laser beacons Each level change delivers better image quality

2005 December 8JEN TMT status46 MCAO technology needs 5 cameras, 5e- rms 3 cameras, 5e- rms 3 each with Today’s 128x128 x 250Hz, 20e- rms read noise Near IR WFS detectors 9 cameras 256x256 x 1kHz 7 cameras, 256x256 x 1kHz 5 each with Today’s 128x128 x 1kHz Visible WFS detectors 10x Today3x TodayToday’s1 x 10 9 operations/sec Real-time computing 4DMs, 21,000 actuators 3 DMs, 9,000 actuators 2 DMs, 2,500 actuators 1 DM, 900 actuators Deformable mirrors 9 lasers, 15W m/m pulsed, AO on uplink 7 lasers, 15W m/m pulsed 5 each with Today’s Technology 2W CW dye, 8W micropulse/ macropulse Na guide star lasers 133 nm180 nm248 nm Today Technolo gy

2005 December 8JEN TMT status47 TMT Reference Design Following a detailed engineering study, the partnership has agreed on a single basic reference design: –30m filled aperture, highly segmented –aplanatic Gregorian (AG) two mirror telescope –f/1 primary –f/15 final focus –Field of view 20 arcmin –Elevation axis in front of the primary –Wavelength coverage 0.31 – 28 µm –Operational zenith angle range 1° thru 65° –Both seeing-limited and adaptive optics observing modes –First generation instrument requirements defined –AO system requirements defined