1. S. Strom, L. Stepp23 August, 2001 NIO GSMT Overview

2. 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.”

3. Goals of the NIO Foster community interaction re GSMT Develop point design Conduct studies of key technical issues and relationship to science drivers Optimize community resources: –emphasize studies that benefit multiple programs, –collaborate to ensure complementary efforts, –give preference to technical approaches that are extensible to even more ambitious projects. Develop a partnership to build GSMT

4. AURA New Initiatives Office Adaptive Optics Ellerbroek/Rigaut (Gemini) Controls George Angeli Opto-mechanics Myung Cho Contracted Studies

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

6. Resources: 2001-2002 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

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

8. Resources: Next Decade $15M in CY 2003-2006 from NOAO base – Enables start of Preliminary Design with partner $25M in CY 2007-2011 from NOAO base Create a ‘wedge’ of ~$10M/yr by 2010 – Enables NOAO funding of Major subsystem Instruments Operations

9. Key Milestones 2Q01: Establish initial science requirements 3Q01: Complete initial instrument concepts 3Q01: Complete initial point design analysis 1Q02: Identify and fund alternate concept studies 2Q02: Identify and fund key technology studies 2Q02: Identify potential US and/or international partners 1Q03: Complete concept trade studies 2Q03: Develop MOUs with partner(s) 2Q03: Establish final science requirements 4Q03: Initiate Preliminary Design 2Q05: Complete Preliminary Design 4Q05: Complete next stage proposal

10. FIRST STEP: UNDERSTAND SCIENCE REQUIREMENTS

11. Developing Science Cases Two community workshops (1998-1999) – 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) – Refine performance goals and requirements

12. 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

13. 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

14. 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 ~ 10000 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

15. 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=5,000 0.1”x0.1” IFU pixel (sub-kpc scale structures) J H K 26.5 25.5 24.0

16. 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

17. 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

18. 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

19. Derived Top Level Requirements

20. NIO Approach Parallel efforts –Address challenges common to all ELTs Wind-loading Adaptive optics Site –Explore “point design” Start from a strawman motivated by science Understand key technical issues through analysis –NB: Point design is simply a starting point! NIO will explore alternate approaches

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

22. Wind Loading 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 Solutions include: –Site selection for low wind speed –Optimizing enclosure design –Dynamic compensation Adaptive Optics Active structural damping

23. Gemini South Wind Test Performed during integration of Gemini Telescope on Cerro Pachon –Enclosure has large vent gates – permits testing a range of enclosure conditions –Dummy mirror has properties equivalent to the real primary mirror, but can be instrumented –M1 is above the EL axis - open to the wind flow (similar to concepts for future larger telescopes)

25. Instrumentation 3-axis anemometers Pressure sensors, 32 places

26. Sensor Locations Ultrasonic anemometer Pressure sensors

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

29. Wind Pressure Structure Function C00030oo

30. Extrapolation to 30 Meters Pressure variation on 30-m mirror about twice 8-m Prms = 0.04d^0.5

31. Summary and Conclusions Wind loading on M1 is strongly dependent on vent gate openings Wind loading on M2 is not strongly dependent on vent gate openings Control algorithm will maintain wind speed at M1 < 3 m/sec With vent gates closed, M1 deformations remain within error budget even in high winds Pressure variations on M1 are larger than average pressure M1 wind deformations are dominated by astigmatism M1 deformations are proportional to RMS pressure variations on surface M1 deformations ~ proportional to (wind velocity at mirror) ² Pressure structure functions fit 0.5 power law Structure functions allow extrapolation to larger telescopes – pressure range for 30m twice that of 8m

32. 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 10 5 800 25cm 25% 86% 30,000 2 x 10 4 125 50cm 2% 61% 8,000 1,500 31 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

33. 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 1.25 0.2 ~ 0.4 1.65 0.4 ~ 0.6 2.20 0.6 ~ 0.8 PSF variations < 1% across FOV

34. Site Evaluation ELT site evaluation more demanding 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

35. Site Evaluation NIO gathering uniform data for sites in: –Northern Chile –Mexico and Southwest US –Hawaii Effort led by NIO staff Parallel effort in Mexico, aligned with NIO- developed criteria

36. POINT DESIGN APPROACH

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

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

39. Point Design: Motivations Enable high-Strehl performance over several arc-minute fields – Stellar populations; galactic kinematics; chemistry Provide a practical basis for wide-field, native seeing-limited instruments –Origin of large-scale structure Enable high sensitivity mid-IR spectroscopy – Detection of forming planetary systems

40. Choices for NIO Point Design Explore prime focus option –attractive enabler for wide-field science –cost-saving in instrument design Assume adaptive M2 –compensate for wind-buffeting –reduce thermal background –deliver enhanced-seeing images Explore a radio telescope approach –possible structural advantages –possible advantages in accommodating large instruments

41. 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

42. 30m Giant Segmented Mirror Telescope Point Design Concept 30m F/1 primary, 2m adaptive secondary GEMINI

43. Key Point-Design Features 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

44. Key Point-Design Features 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

45. Key Point-Design Features 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

46. 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 0.2-0.3” 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

47. 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

48. 30m GSMT Initial Point-Design Structural Model Horizon Pointing - Mode 1 = 2.16 Hz

49. Response to Wind Need to quantify wind effects, and develop control system responses to correct pointing, focus, and optical aberrations

50. Modeling of Active Corrections We are considering two approaches: –Partition mode shapes + line-of sight equations –Ray-tracing mode shapes

51. Structural Mode Shapes M1 Surface

52. Modal Partitioning For each vibration mode shape –Separate group of nodes representing M1 –Determine Zernike polynomials for M1 mode shape by least- squares fit –Determine rigid-body motions of M2, calculate effect on image motion and aberrations l Combine participation of all modes in random vibration analysis based on a defined wind input, to calculate the PSD, and RMS amplitude of: –image motion –piston and focus –astigmatism –coma

53. Ray Tracing of Mode Shapes For each vibration mode shape –Determine rigid-body motions of M1 and M2 –Develop an “interferogram” phase map from the residual aberrations on M1 –Input information to an optical analysis program (i.e., Code V) –Determine image motion and Zernike polynomials that describe the wavefront at the focal surface l Combine participation of all modes in random vibration analysis based on a defined wind input, to calculate the PSD, and RMS amplitude of: –image motion –piston and focus –astigmatism –coma

54. 0.0010.010.1110100 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

55. Enclosure studies Initial enclosure studies will focus on: –Ability to protect telescope from wind –Understanding cost issues

56. Some Possible Enclosure Designs

57. AO Systems Adaptive secondary mirror Adaptive mirror in prime focus corrector Multi-conjugate wide-field AO High-order narrow-field conventional AO

58. 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

59. Key Point-Design Features 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)

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

61. Boundary Layer Compensation Median natural seeing (upper solid line) and median compensated seeing at V band for a single deformable mirror with actuator pitches of 25 cm (solid), 50 cm (dotted) and 1-m (dashed). (From Rigaut, 2001)

62. 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)

63. MCAO System

64. Instruments Telescope, AO and instruments must be developed as an integrated system NIO team developing design concepts – Multi-Object, Multi-Fiber, Optical Spectrograph – Near IR Deployable Integral Field Spectrograph – MCAO-fed near-IR imager – Mid-IR, High Dispersion, AO Spectrograph Build on extant concepts where possible Define major design challenges Identify needed technologies

65. Multi-Object Multi-Fiber Optical Spectrograph (MOMFOS) 20 arc-minute field 60-meter fiber cable 700 0.7” fibers 3 spectrographs, ~230 fibers each VPH gratings Articulated collimator for different resolution regimes Resolution Example ranges with single grating R= 1,000 350nm – 650nm R= 5,000 470nm – 530nm R= 20,000 491nm – 508nm Detects 13% - 23% of photons hitting the 30m primary

66. Prime Focus MOMFOS Barden et al (2001)

67. Key Point-Design Features (MOMFOS) 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

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

69. MOMFOS Spectrograph Micro-Lens Relay 500 mm diameter fiber fed by two micro-lenses with spherical surfaces 100% of light couples into fiber. Field stop limits light to 0.72” aperture

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

71. Spot Diagrams for MOMFOS 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)

72. MOMFOS Spectrograph Predicted Efficiency

73. Near Infra-Red Deployable Integral Field Spectrograph (NIRDIF) MCAO fed 1.5 to 2.0 arc-minute FOV 1 – 2.5  m wavelength coverage Deployable IFU units 1.5 arc-second FOV per IFU probe 31 slices per IFU probe (0.048” per slice) ~26 deployable units

74. Near Infra-Red Deployable Integral Field Spectrograph (NIRDIF) Relay optics contained in deployable arm. 1.5 by 1.5 arc-second field of view. f/38 to f/128 converter from MCAO field to image slicer. Telecentric input and output. Cold stop located within relay.

75. Near Infra-Red Deployable Integral Field Spectrograph (NIRDIF) f/128 image slicer with 31 slices converted to f/11.5 for the spectrograph. Side view showing top, middle, and bottom slices. Top view showing top, middle, and bottom slices.

76. Near Infra-Red Deployable Integral Field Spectrograph (NIRDIF) Spectrographs 2 IFU’s per spectrograph ~13 spectrographs R = 1000 to 10,000 Z, J, H, and K spectral coverage (not simultaneous) 2 K detector format assumed

77. Mid-Infrared High Dispersion AO Spectrograph (MIHDAS) Adaptive Secondary AO feed On-Axis, Narrow Field/Point Source R=120,000 3 spectrographs 2-5  m (small beamed, x-dispersed), 0.2 arc-second slit length 10-14  m (x-dispersed), 1 arc-second slit 16-20  m (x-dispersed), 1 arc-second slit 10-14  m spectrograph likely to utilize same collimator as 16-20  m instrument. Different Gratings and Camera. 2-5  m spectrograph may require additional AO mirrors.

78. Mid-Infrared High Dispersion AO Spectrograph (MIHDAS) 16-20 mm spectrograph will be large. Diffraction limit at 20 microns is about ¼ arc-second, comparable to native seeing limit. Overall Echelle grating is 1.5 meters in length! Overall instrument is expected to take up a volume of about 3 by 3 by 3 meters! All of which needs to be cryogenically cooled. Instrument to be located at Cass location and move with the telescope.

79. R10 Echelle (84°) 7 mm/line 150 by 1500 mm\ m = 696 - 804 16 to 20  m 1” slit length.28” slit width 1024 by 1024 Si:As detector 45 l/mm X-disperser 26.5° blaze ~360 mm Mid-Infrared High Dispersion AO Spectrograph (MIHDAS)

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

81. MCAO Near-IR Imager f/38 input with 1:1 reimaging optics 1.5 to 2 arc-minute field of view Monolithic imager -  5.5 mm/arc-second plate scale!  685 mm sized detector array for 2 arc-min field!  28K by 28K detector!  7 by 7 mosaic of 4K arrays  0.004 arc-second per pixel sampling Alternative approach is to have deployable capability for imaging over a subset of the total field.

82. Instrument Locations on Telescope Prime Focus Co-moving Cass Fixed Gravity Cass Direct-fed Naysmyth Fiber-fed Naysmyth View showing Fixed Gravity Cass instrument

83. Instrument Locations on Telescope View showing Co-moving Cass instrument

84. Instrument Locations on Telescope MCAO-fed NIRDIF or MCAO Imager Cass-fed MIHDAS Fiber-fed MOMFOS

85. Information on AURA NIO activities is available at: www.aura-nio.noao.edu