NIO GSMT Overview VLOT/GSMT WORKSHOP Victoria, BC 17 JULY, 2001 S. Strom, L. Stepp

AURA NIO: Mission In response to AASC call for a GSMT, AURA formed a New Initiatives Office (NIO) –collaborative effort between NOAO and Gemini to explore design concepts for a GSMT NIO mission “ to ensure broad astronomy community access to a 30m telescope contemporary in time with ALMA and NGST, by playing a key role in scientific and technical studies leading to the creation of a GSMT.”

Goals of the NIO Foster community interaction on GSMT Develop point design Conduct studies of key technical issues and relationship to science drivers Optimize community resources: –explore design options that yield cost savings, –emphasize studies that benefit multiple programs, –collaborate to ensure complementary efforts, –give preference to technologies that are extensible to even more ambitious projects.

AURA New Initiatives Office

Comparative performance of a 30m GSMT with a 6.5m NGST Assuming a detected S/N of 10 for NGST on a point source, with 4x1000s integration GSMT advantage NGST advantage R = 10,000 R = 1,000 R = 5

GSMT/NGST at High Spectral Resolution

Developing Science Cases Two community workshops ( ) – Broad participation; wide-ranging input Tucson task group meetings (SEP 2000) – Large-scale structure; galaxy assembly – Stellar populations – Star and planet formation NIO working groups (MAR 01 – SEP 01) – Develop quantitative cases; simulations NIO-funded community task groups (CY 2002) NIO-funded community workshop (CY 2002) – Define “Science Reference Mission”

KEY SCIENCE ENABLED BY GSMT Origin of structure in the universe: from the big bang to planetary systems Najita et al (2000,2001)

Tomography of the Universe Goals: Map out large scale structure for z > 3 Link emerging distribution of gas; galaxies to CMB Measurements: Spectra for 10 6 galaxies (R ~ 2000) Spectra of 10 5 QSOs (R ~15000) Key requirements: 20’ FOV; >1000 fibers Time to complete study with GSMT: 3 years Issues –Refine understanding of sample size requirements –Spectrograph design

Mass Tomography of the Universe z~0.5 Existing Surveys + Sloan z~3 Hints of Structure at z=3 (small area) 100Mpc (5 O x5 O ), 27AB mag (L* z=9), dense sampling GSMT1.5 yr Gemini50 yr NGST140 yr

Tomography of Galaxies and Pre-Galactic Fragments Goals: Determine gas and stellar kinematics Quantify SFR and chemical composition Measurements: Spectroscopy of H II complexes and underlying stars Key requirements: Deployable IFUs feeding R ~ spectrograph Wide FOV to efficiently sample multiple systems Time to complete study with GSMT: ~1 year Issues –Modeling surface brightness distribution –Understanding optimal IFU ‘pixel’ size

Tomography of Individual Galaxies out to z ~3 Determine the gas and stellar dynamics within individual galaxies Quantify variations in star formation rate – Tool: IFU spectra [R ~ 5,000 – 10,000] GSMT 3 hour, 3  limit at R=5, ”x0.1” IFU pixel (sub-kpc scale structures) J H K

Origins of Planetary Systems Goals: – Understand where and when planets form – Infer planetary architectures via observation of ‘gaps’ Measurements: Spectra of 10 3 accreting PMS stars (R~10 5 ;  ) Key requirements: On axis, high Strehl AO; low emissivity Time to complete study with GSMT: 2 years Issues Understand efficacy of molecular ‘tracers’ Trades among emissivity; sites; telescope & AO design

Probing Planet Formation with High Resolution Infrared Spectroscopy Planet formation studies in the infrared (5-30µm):  Probe forming planets in inner disk regions  Residual gas in cleared region low  emission  Rotation separates disk radii in velocity  High spectral resolution high spatial resolution  8-10m telescopes with high resolution (R~100,000) spectrographs can detect the formation of Jupiter-mass planets in disks around nearby stars (d~100pc). S/N=100, R=100,000, >4  m Gemini out to 0.2kpc sample ~ 10s GSMT 1.5kpc ~100s NGST X

Stellar Populations Goals: Quantify IMF in different environments Quantify ages; [Fe/H]; for stars in nearby galaxies Develop understanding of galaxy assembly process Measurements: Spectra of ~ 10 5 stars in rich, forming clusters (R ~ 1000) CMDs for selected areas in local group galaxies Key requirements: MCAO delivering 2’ FOV; MCAO-fed NIR spectrograph Time to complete study with GSMT: 3 years Issues – MCAO performance in crowded fields

GSMT System Considerations Science Mission - DRM’s GSMT Concept (Phase A) Support & Fabrication Issues Active Optics (aO) Site Characteristics Enclosure protection Adaptive Optics Instruments Full System Analysis

NIO Approach Parallel efforts –Address challenges common to all ELTs Wind-loading Adaptive optics Site –Explore point design Start from a strawman Understand key technical issues

Enemies Common to all ELTs l Wind….. l The Atmosphere……

Wind Loading l Primary challenge may be wind buffeting –More critical than for existing telescopes Structural resonances closer to peak wind power Wind may limit performance more than local seeing l Solutions include: –Site selection for low wind speed –Optimizing enclosure design –Dynamic compensation Adaptive Optics Active structural damping

Animation Wind pressure: C00030oo test_2, day_2, Azimuth angle=00, Zenith angle=30, wind_gate:open, open; wind speed=11 m/s

Wind Pressure Structure Function C00030oo

How to scale to 30 meters: D(d) = d M RMS pressure differences Spatial scale

The Gemini South wind test results are available on the NIO Web site at:

AO Technology Constraints: DMs and Computing power (50m telescope; on axis) r 0 (550 nm) = 10cm No. of Computer CCD pixel Actuator pitch S(550nm) S(1.65  m) actuators power rate/sensor (Gflops) (M pixel/s) 10cm 74% 97% 200,000 9 x cm 25% 86% 30,000 2 x cm 2% 61% 8,000 1, SOR (achieved) 789 ~ 2 4 x 4.5 Early 21 st Century technology will keep AO confined to > 1.0  m for telescopes with D ~ 30m – 50m

AO Technology Constraints: Guide stars and optical quality MCAO system analysis by Rigaut & Ellerbroek (2000): 30 m telescope 2 arcmin field 9 Sodium laser constellation 10 watts each 4 tip/tilt stars (1 x 17, 3 x 20 Rmag) Telescope residual errors ~ 100 nm rms Instrument residual errors ~ 70 nm rms System performance: (  m) Delivered Strehl ~ ~ ~ 0.8 PSF variations < 1% across FOV

Site Evaluation l ELT site evaluation more demanding l Evaluation criteria include –surface and high altitude winds –turbulence profiles –transmission –available clear nights (long-term averages) –cirrus cover (artificial guide star performance) –light pollution –accessibility –available local infrastructure –land ownership issues

Site Evaluation l NIO gathering uniform data for sites in: –Northern Chile –Mexico and Southwest US –Hawaii

Point Design: Philosophy l Select plausible design that addresses key science requirements l Identify key technical challenges l Focus analysis on key challenges l Evaluate strengths and weaknesses –guide initial cost-performance evaluation –inform concept design trades l Point design is only a strawman!

Point Design: Motivations l Provide a practical basis for wide-field, native seeing-limited instruments –science drivers strong l Explore a radio telescope approach –possible structural advantages elevation bearing size comparable to primary –possible advantages in accommodating large instruments

Point Design: End-to End Approach Science Requirements (including instruments) Error Budget Control systems Enclosure concept –Interaction with site, telescope and budget Telescope structure –Interaction with wind, optics and instruments Optics –Interaction with telescope, aO/AO systems and instruments AO/MCAO –Interaction with telescope, optics, and instruments Instruments –Interaction with AO and Observing Model

Derived Top Level Requirements

30m Giant Segmented Mirror Telescope Point Design Concept 30m F/1 primary, 2m adaptive secondary GEMINI

Key Point-Design Features l Paraboloidal primary –Advantage: Good image quality over 20 arcmin field with only 2 reflections Seeing-limited observations in visible Mid-IR –Disadvantage: Higher segment fabrication cost

Key Point-Design Features l F/1 primary mirror –Advantages: Reduces size of enclosure Reduces flexure of optical support structure Reduces counterweights required –Disadvantages: Increased sensitivity to misalignment Increased asphericity of segments

Key Point-Design Features l Radio telescope structure –Advantages: Cass focus can be located just behind M1 Allows small secondary mirror – can be adaptive Allows MCAO system ahead of Nasmyth focus –Disadvantage: Requires counterweight Sweeps out larger volume in enclosure

Zernike modes Bandwidth [Hz] ~100 ~50 ~20 ~10 2 Controls Approach: Offloading Decentralized Controllers aO (M1) AO (M2) Main Axes LGS MCAO Secondary rigid body temporal avg spatial & temporal avg spatial avg

GSMT Control Concept LGSs provide full sky coverage Deformable M2 : First stage MCAO, wide field seeing improvement and M1 shape control 10-20’ field at ” seeing 1-2’ field fed to the MCAO module  M2: rather slow, large stroke DM to compensate ground layer and telescope figure,  or to use as single DM at >3  m. (~8000 actuators)  Dedicated, small field (1-2’) MCAO system (~4-6DMs). Focal plane Active M1 (0.1 ~ 1Hz) 619 segments on 91 rafts

Enabling Techniques Active and Adaptive Optics –Active Optics already integrated into Keck, VLT, Gemini, Subaru, Magellan, … –Adaptive Optics “added” to CFHT, Keck, Gemini, VLT, … Active and Adaptive Optics will have to be integrated into GSMT Telescope and Instrument concepts from the start

Enclosures Design options under study

30m GSMT Initial Point-Design Structural Model Horizon Pointing - Mode 1 = 2.16 Hz

Response to Wind Current concept will now go through “second iteration” of design in response to wind analysis

Goal: 8000 actuators 30cm spacing on M1 Options: low- to high-order Compensate for wind- driven M1 distortions Deliver high Strehl, mid-IR images with low emissivity Deliver high-Strehl, near-IR images Adaptive M2 Intrinsic to Point Design

Key Point-Design Features l 2m diameter adaptive secondary mirror –Advantages: Correction of low-order M1 modes Enhanced native seeing Good performance in mid-IR First stage in high-order AO system –Disadvantages: Increased difficulty (i.e., cost)

Sky Coverage vs Wavelength; Strehl for an Adaptive M2 (single laser guide star; Rigaut, 2001)

GSMT Implementation Concept - MCAO/AO foci and instruments MCAO optics moves with telescope Narrow field AO or narrow field seeing limited port MCAO Imager at vertical Nasmyth elevation axis 4m Oschmann et al (2001)

MCAO Near-IR Imager (1:1 Unfolded) 40 mm Pupil ~ 2 arc minute field

Instruments Telescope, AO and instruments must be developed as an integrated system NIO team developing design concepts – Prime focus wide-field MOS – MCAO-fed near-IR MOS – MCAO-fed near-IR imager – AO-fed mid-IR HRS – Wide-field deployable IFU spectrograph Build on extant concepts where possible Define major design challenges Identify needed technologies

Optical “seeing improvement” using low order AO correction 16 consecutive nights of adaptive optics the CFHT Image profiles are Lorenzian

Multi-Object Multi-Fiber Optical Spectrograph (MOMFOS) 20 arc-minute field 60-meter fiber cable ” fibers 4 spectrographs, 200 fibers each VPH gratings Articulated collimator for different resolution regimes Resolution Example ranges with single grating R= 1, nm – 650nm R= 5, nm – 530nm R= 20, nm – 508nm Detects 13% - 23% of photons hitting the 30m primary

Prime Focus MOMFOS Barden et al (2001)

Key Point-Design Features l MOMFOS located at prime focus –Advantages Fast focal ratio leads to reasonably-sized instrument Adaptive prime focus corrector allows enhanced seeing performance –Disadvantages Issues of interchange with M2

MOMFOS with Prime Focus Corrector Conceptual design fits in a 3m dia by 5m long cylinder

R=20000 mode R=5000 mode R=1000 mode MOMFOS Spectrograph 500mm pupil; all spherical optics

Spot Diagrams for Spectrograph R=1000 case with 540 l/mm grating. R=5000 case with 2250 l/mm grating. 350 nm440 nm500 nm560 nm650 nm 470 nm485 nm500 nm515 nm530 nm On-axis Circle is 85 microns equal to size of imaged fiber. Barden et al (2001)

Key NIO Activities in 2001 Core NIO team in place and working Science case studies underway Point design structural concept developed by SGH Wind loading test data analyzed AO system concept being developed Instrument concepts MCAO imager MCAO NIR MOS IFU spectrograph Wide-field prime-focus MOS High resolution mid-IR spectrograph Chilean site characteristics assembled Initial analysis of point design underway

Objectives: Next 2 years l Develop point design for GSMT & instruments l Develop key technical solutions –Adaptive optics –Active compensation of wind buffeting –Mirror segment fabrication l Investigate design-to-cost considerations l Involve the community in defining GSMT science and engineering requirements l Involve the community in defining instrumentation options; technology paths l Carry out conceptual design activities that support and complement other efforts l Develop a formal partnership to build GSMT

Objectives: Next Decade Complete GSMT preliminary design (2Q 2005) Complete final design (Q4 2007) Serve as locus for –community interaction with GSMT consortium –ongoing operations –defining; providing support capabilities –defining interactions with NGST

Key Milestones 2Q01: Establish initial science requirements 3Q01: Complete initial instrument concepts 3Q01: Complete initial point design analysis 2Q02: Identify key technology studies 1Q03: Fund technology studies 1Q03: Complete concept trade studies 2Q03: Develop MOUs with partner(s) 2Q03: Initiate Preliminary Design 4Q03: Complete SRM; establish science requirements 2Q05: Complete Preliminary Design 4Q05: Complete next stage proposal

Resources: NIO activities: $3.6M – Support core NIO staff (‘skunk works team’) Analyze point design Develop instrument and subsystem concepts – Support Gemini and NOAO staff to Explore science and instrument requirements Develop systems engineering framework – Support community studies: Enable community efforts: science; instruments Enable key external engineering studies Support alternative concept studies

Resources: Next Decade $15M in CY from NOAO base – Enables start of Preliminary Design with partner $25M in CY from NOAO base Create a ‘wedge’ of ~$10M/yr by 2010 – Enables NOAO funding of Major subsystem Instruments Operations