1. AURA New Initiatives Office Euro50 - GSMT - XLT MeetingLMS, 08/02/02 The Giant Segmented Mirror Telescope

2. AURA New Initiatives Office Euro50 - GSMT - XLT MeetingLMS, 08/02/02 The USA Decadal Review In May 2000, the US astronomy decadal review committee recommended, as its highest priority ground-based initiative, the construction of a 30-meter Giant Segmented Mirror Telescope (GSMT) In response, AURA formed a New Initiatives Office (NIO) to support scientific and technical studies leading to the creation of a GSMT NIO is a joint venture of the National Optical Astronomy Observatory (NOAO) and the Gemini Observatory Goal is to ensure broad astronomy community access to a 30m telescope contemporary with NGST.

3. AURA New Initiatives Office Euro50 - GSMT - XLT MeetingLMS, 08/02/02 N IO Organization NIO Management Board William Smith -- President of AURA Jeremy Mould -- Director of NOAO Matt Mountain -- Director of Gemini Observatory Project Scientist Steve Strom Program Manager Larry Stepp System Scientist Brooke Gregory Opto-Mechanical Myung Cho Mechanical Designer Rick Robles Structures Paul Gillett Controls George Angeli Adaptive Optics Ellerbroek - Gemini Instruments Barden - NOAO Optics Hansen - Gemini Sites Walker - NOAO Admin. Assistant Jennifer Purcell

4. AURA New Initiatives Office Euro50 - GSMT - XLT MeetingLMS, 08/02/02 AURA New Initiatives Office Approach to GSMT Design Three Parallel efforts: Understand the scientific context for GSMT in NGST / ALMA era Develop the key science requirements Address challenges common to all ELTs Site testing and selection Cost-effective segment fabrication Characterization of wind loading Hierarchical control systems Adaptive optics Cost control techniques Develop a Point Design Based on initial science goals & instrument concepts

5. AURA New Initiatives Office Euro50 - GSMT - XLT MeetingLMS, 08/02/02 Science Programs Science Theme Large Scale Structure Planet Formation Environments Tomography of Galaxies and pre-Galactic Fragments Resolved Stellar Populations High-dynamic range science Field of ViewWide: >20 arc minute Narrow: <5 arc second 2 arc minute2 arc minunteNarrow: <5 arc second Wavelength0.4  m < < 1.1  m3  m < < 25  m1  m < < 2.5  m Image qualitySeeing limited < 0.5 arc second Diffraction-limited low-emissivity < 0.1 arcsecondDiffraction limitedStrehl ratio > 0.9 InstrumentationMulti-Object Spectrograph R = 1000 - 5000 High-resolution spectrograph R = 100,000 Deployable IFU spectrograph R = 5000 – 10,000 ImagerCoronagraph

6. AURA New Initiatives Office Euro50 - GSMT - XLT MeetingLMS, 08/02/02 Site Testing and Selection lSurvey of candidate sites by remote sensing (satellite data) Regions of interest: Mauna Kea Western United States and Mexico Chile Parameters determined: Cloud cover Precipitable water vapor Collaborators: Cornell ESO University of Tokyo CELT UNAM & INAOE (Mexico)

7. AURA New Initiatives Office Euro50 - GSMT - XLT MeetingLMS, 08/02/02 Site Testing and Selection lConstruction of turbulence profilometer (MASS – Multi-Aperture Scintillation Sensor) Uses scintillation measurements of a single star to measure: Isoplanatic angle, characteristic strengths and altitudes of the few dominant turbulence layers Integral seeing producing by the whole atmosphere

8. AURA New Initiatives Office Euro50 - GSMT - XLT MeetingLMS, 08/02/02 Site Testing and Selection lAtmospheric turbulence modeling and measuring Direct measurements of seeing and wind speed Computational fluid dynamics Collaborators CELT UNAM (Mexico) Cornell Digital elevation model of Chajnantor region

9. AURA New Initiatives Office Euro50 - GSMT - XLT MeetingLMS, 08/02/02 Site Testing and Selection lSodium layer measurements at Cerro Tololo Collaborating on Gemini study to answer questions about variation of sodium layer height, thickness and column density with: Latitude Season Time of night 300mw laser launched from laser room on Cerro Tololo

10. AURA New Initiatives Office Euro50 - GSMT - XLT MeetingLMS, 08/02/02 Characterization of Wind Loading Test at Gemini South lOpportunity arose during integration of Gemini South to do a full-scale wind test in realistic conditions lGemini enclosure has large vent gates – permits testing a range of enclosure conditions lGemini dummy mirror has equivalent properties as the real primary mirror, but can be instrumented lGemini M1 is above the EL axis - open to the wind flow (similar to concepts for future larger telescopes)

11. AURA New Initiatives Office Euro50 - GSMT - XLT MeetingLMS, 08/02/02 Gemini 8-meter Telescope

12. AURA New Initiatives Office Euro50 - GSMT - XLT MeetingLMS, 08/02/02 Sensor locations 3-axis anemometers Pressure sensors, 32 places

13. AURA New Initiatives Office Euro50 - GSMT - XLT MeetingLMS, 08/02/02 Sensor Locations Pressure sensors Ultrasonic anemometer

14. AURA New Initiatives Office Euro50 - GSMT - XLT MeetingLMS, 08/02/02 Simultaneous Animations (c00030oo) Wind Pressure (N/m 2 ) Mirror Deformation (microns) Wind Speed at 5 Locations (m/sec)

15. AURA New Initiatives Office Euro50 - GSMT - XLT MeetingLMS, 08/02/02 0.0010.010.1110100 Zernike modes Bandwidth [Hz] ~100 ~50 ~20 ~10 2 Controls Approach: Hierarchical Subsystems aO (M1) AO (M2) Main Axes LGS MCAO Secondary rigid body temporal avg spatial & temporal avg spatial avg

16. AURA New Initiatives Office Euro50 - GSMT - XLT MeetingLMS, 08/02/02 Point Design Key Features Fast aspheric primary –Stigmatic image after two reflections Radio telescope-type design Structural advantages Accommodates large instruments Adaptive secondary –Wind-buffeting compensation –Atmospheric correction in IR, with low emissivity –First stage in higher-order adaptive systems Prime focus instrument –Convenient plate scale for seeing-limited observations –Enables wide-field science

17. AURA New Initiatives Office Euro50 - GSMT - XLT MeetingLMS, 08/02/02 Optical Design M1 diameter: 30 meters M1 focal ratio: f/1 M2 diameter: 2 meters M2 focal ratio: f/18.75 Optical design: Classical Cassegrain

18. AURA New Initiatives Office Euro50 - GSMT - XLT MeetingLMS, 08/02/02 Radio Telescope Structural Design lLightweight steel truss structure lFast primary focal ratio lSmall secondary mirror lM2 supported on tripod structure lElevation axis behind M1 Span between elevation bearings is less than M1 diameter Allows direct load path

19. AURA New Initiatives Office Euro50 - GSMT - XLT MeetingLMS, 08/02/02 Initial Point Design Structure Concept developed by Joe Antebi of Simpson Gumpertz & Heger Based on radio telescope Space frame truss Single counterweight Cross bracing of M2 support

20. AURA New Initiatives Office Euro50 - GSMT - XLT MeetingLMS, 08/02/02 Initial Point Design Structure Plan View of StructurePattern of segments Gemini

21. AURA New Initiatives Office Euro50 - GSMT - XLT MeetingLMS, 08/02/02 Initial Structural Analysis Horizon Pointing - Mode 1 = 2.16 Hz

22. AURA New Initiatives Office Euro50 - GSMT - XLT MeetingLMS, 08/02/02 A Few Parameters from the Structural Analysis Total weight of elevation structure – 700 tonnes Total moving weight – 1400 tonnes Gravity deflections ~ 5-25 mm –Primarily rigid-body tilt of elevation structure Lowest resonant frequencies ~ 2 Hz Large size and low resonant frequency make wind buffeting a key issue.

23. AURA New Initiatives Office Euro50 - GSMT - XLT MeetingLMS, 08/02/02 Current structural concept

24. AURA New Initiatives Office Euro50 - GSMT - XLT MeetingLMS, 08/02/02 Primary Mirror Segments Segment dimensions –1.15-m across flats -- 1.33-m corner to corner –50 mm thickness Number of segments: 618 Maximum departure from sphere 110 microns –Comparable to Keck Axial support is 18-point whiffletree –FEA Gravity deflection 15 nm RMS

25. AURA New Initiatives Office Euro50 - GSMT - XLT MeetingLMS, 08/02/02 One-piece Central Raft

26. AURA New Initiatives Office Euro50 - GSMT - XLT MeetingLMS, 08/02/02 Stray Light Baffles If Needed Primary baffle: 14 m long Secondary baffle: 3 m diamater Fully baffled field of view: 5 arc min

27. AURA New Initiatives Office Euro50 - GSMT - XLT MeetingLMS, 08/02/02 Controllable Elements Active Systems: Active structural elements – Active alignment – Active damping M2 rigid body motion – ~ 5-10 Hz – Five axes M1 segment figure control – Based on look-up table ~ 0.1 Hz – Astigmatism, focus, trefoil, coma M1 segment rigid body position – ~ 1 Hz – Piston, tip & tilt

28. AURA New Initiatives Office Euro50 - GSMT - XLT MeetingLMS, 08/02/02 Controllable Elements Adaptive Systems: High-order narrow-field conventional AO –~ 10,000 – 50,000 actuators Multi-conjugate wide-field AO –~ 3 DMs; ~ 8500 actuators –Laser Guide Stars Adaptive secondary mirror –~ 20-50 Hz –~ 2400 actuators Adaptive mirror in prime focus corrector

29. AURA New Initiatives Office Euro50 - GSMT - XLT MeetingLMS, 08/02/02 Active and Adaptive Optics will be integrated into Telescope and Instrument concepts from the start.

30. AURA New Initiatives Office Euro50 - GSMT - XLT MeetingLMS, 08/02/02 Instruments NIO currently developing design concepts for 5 instruments: –Multi-Object, Multi-Fiber, Optical Spectrograph – MOMFOS –Near IR Deployable Integral Field Spectrograph – NIRDIF –MCAO-fed near-IR imager –Mid-IR, High Dispersion, AO Spectrograph – MIHDAS –Diffraction-Limited Near IR Coronagraph

31. AURA New Initiatives Office Euro50 - GSMT - XLT MeetingLMS, 08/02/02 Multi-Object Multi-Fiber Optical Spectrograph (MOMFOS) Located at prime focus

32. AURA New Initiatives Office Euro50 - GSMT - XLT MeetingLMS, 08/02/02 Multi-Object Multi-Fiber Optical Spectrograph (MOMFOS) Located at prime focus

33. AURA New Initiatives Office Euro50 - GSMT - XLT MeetingLMS, 08/02/02 Diffraction-limited Coronagraph Located at co-moving Cassegrain focus

34. AURA New Initiatives Office Euro50 - GSMT - XLT MeetingLMS, 08/02/02 Instrument Locations Prime Focus

35. AURA New Initiatives Office Euro50 - GSMT - XLT MeetingLMS, 08/02/02 Instrument Locations Co-moving Cassegrain Focus

36. AURA New Initiatives Office Euro50 - GSMT - XLT MeetingLMS, 08/02/02 Instrument Locations Fixed-gravity Cassegrain Focus

37. AURA New Initiatives Office Euro50 - GSMT - XLT MeetingLMS, 08/02/02 Instrument Locations MCAO-fed Nasmyth Focus

38. AURA New Initiatives Office Euro50 - GSMT - XLT MeetingLMS, 08/02/02 MCAO System

39. AURA New Initiatives Office Euro50 - GSMT - XLT MeetingLMS, 08/02/02 Mayall, Gemini and GSMT Enclosures at same scale Mayall Gemini GSMT

40. AURA New Initiatives Office Euro50 - GSMT - XLT MeetingLMS, 08/02/02 McKale Center – Univ of Arizona

41. AURA New Initiatives Office Euro50 - GSMT - XLT MeetingLMS, 08/02/02 GSMT – at same scale

42. AURA New Initiatives Office Euro50 - GSMT - XLT MeetingLMS, 08/02/02 Some Possible GSMT Enclosure Designs

43. AURA New Initiatives Office Euro50 - GSMT - XLT MeetingLMS, 08/02/02 Plans for the Next 10 Months l Complete “GSMT Book” in electronic form – will be available next month at: www.aura-nio.noao.edu lInvolve community in understanding GSMT scientific context lContinue work on point design lDevelop integrated modeling of telescope response to disturbances (mainly wind) lContinue site testing efforts lDevelop cost estimates & cost-reduction strategies

44. AURA New Initiatives Office Euro50 - GSMT - XLT MeetingLMS, 08/02/02 Plans for the Next 10 Months l Develop collaborations to work on: Site testing Segment fabrication methods Characterization of wind loading Adaptive optics Development of cost estimates and estimating methods lBuild partnership to proceed with GSMT design