1. Área de Instrumentación NAHUAL Mechanical Concept Current Status F. Javier Fuentes Instituto de Astrofísica de Canarias September 02 2008

2. Área de Instrumentación F. Javier Fuentes Instituto de Astrofísica de Canarias 2  It is the idea a part of the Nahual Consortium has about the present state and desired future development of the mechanical architecture of the instrument.  It is just a proposal for discussion. It is fully opened to all the ideas, comments, suggestions,… Nahual is a very complex instrument and it is not an easy task to put it on the best design path.  It is the input to the mechanical WBS and schedule proposals. They will be presented and discussed on session 4 this meeting. What this talk is?

3. Área de Instrumentación F. Javier Fuentes Instituto de Astrofísica de Canarias 3  Spectral Domain: 1 – 2.4 µm  Spectral Resolution > 50.000  Radial Velocity Accuracy: 1 m/s (1 hr to days/months/years)‏  Simultaneous Wavelength Calibration  No moving parts Science Requirements Main Mode

4. Área de Instrumentación F. Javier Fuentes Instituto de Astrofísica de Canarias 4  Spectral Domain: 0.9 – 2.5 µm  Spectral Resolution 500 to 61.000  Long Slit / Image Slicer  AO needed on some modes  Wavelength Tuning  Cold mechanisms needed to change between configurations  To be implemented ONLY if they are compatible with the Main Mode architecture/functionality/operation Science Requirements Optional Modes

5. Área de Instrumentación F. Javier Fuentes Instituto de Astrofísica de Canarias 5  Working Temperature < 100 K (cryogenic environment)‏  Image Stability 0.1 to 0.01 pixel According the Radial Velocity Error Budget (TBD)‏ Specified values according similar instruments  Temperature Stability in the Cold Bench < 0.01 K According the Zemax-Ansys Instrument Model (TBD)‏ Specified values according similar instruments  Time Stability 1 hr to years According the Calibration Procedure (TBD)‏  No Cold Mechanisms involved  Located in the GTC Nasmyth platform Mechanical Functional Baseline Main Mode

6. Área de Instrumentación F. Javier Fuentes Instituto de Astrofísica de Canarias 6  GIANO @ TNG Spectral Range: 0.9 – 2.5 µm (cryogenic)‏ Spectral Resolution > 46.000 RV accuracy < 10 m/s (< 0.1 K)‏  PRVS @ GEMINI Spectral Range: 0.9 – 1.8 µm (not fully cryogenic)‏ Spectral Resolution > 70.000 RV accuracy < 3 m/s long-term (< 1 m/s goal)‏ Similar Instruments

7. Área de Instrumentación F. Javier Fuentes Instituto de Astrofísica de Canarias 7  SPIROU @ CFHT Spectral Range: 0.9 – 2.4 µm (cryogenic)‏ Spectral Resolution > 50.000 (70.000 goal)‏ RV accuracy < 1 m/s (< 0.01 K)‏  HARPS @ 3.6 m Telescope Spectral Range: visible (non-cryogenic)‏ Spectral Resolution > 120.000 Long-term RV accuracy < 1 m/s (< 0.01 K)‏ Similar Instruments

8. Área de Instrumentación F. Javier Fuentes Instituto de Astrofísica de Canarias 8 Optical Layout. Main Mode Echelle Cross Disperser FP1 FP2 OAP1-OAP2 OAP3 Camera Detector

9. Área de Instrumentación F. Javier Fuentes Instituto de Astrofísica de Canarias 9 Sizes of Optical Components ElementClear aperture (mm)‏ FP1~ 2 x 2 OAP1, OAP2  109 ECHELLE109 x 220 FLD1~ 10 x 10 FP2~ 2 x 2 OAP3  109 CROSS DISP  109 DETECTOR (HAWAII-2)‏36.8

10. Área de Instrumentación F. Javier Fuentes Instituto de Astrofísica de Canarias 10 Mechanical Layout. Fractal Proposal

11. Área de Instrumentación F. Javier Fuentes Instituto de Astrofísica de Canarias 11 Auxiliary Module. Fractal Proposal

12. Área de Instrumentación F. Javier Fuentes Instituto de Astrofísica de Canarias 12 Calibration Module. Fractal Proposal Integrating sphere and lamps Gas cell Cryostat window IR camera

13. Área de Instrumentación F. Javier Fuentes Instituto de Astrofísica de Canarias 13 System architecture.Present status  Mechanical architecture proposed by Fractal is partially driven by the cryogenic Auxiliary Module (Optional Mode) configuration, as well as the configuration/position of the Calibration Module  A new cryogenic layout, only shaped by the Main Mode configuration (according the science requirements), is under study  The space around the entrance window is very crowded. The configuration and position of the Calibration Module will be optimized after the Main Mode architecture is established  The feasibility of the Optional Modes will be studied after the Main Mode architecture is established

14. Área de Instrumentación F. Javier Fuentes Instituto de Astrofísica de Canarias 14 Mechanical Layout. Main Mode

15. Área de Instrumentación F. Javier Fuentes Instituto de Astrofísica de Canarias 15 Mechanical Layout. Main Mode

16. Área de Instrumentación F. Javier Fuentes Instituto de Astrofísica de Canarias 16 Cryogenics concept. Present status  The design of Nahual will be based on Giano’s highly stable cryogenics concept. Recent cold tests of Giano show an actively controlled temperature stability better than 0.01 K for short periods of time (~2 hours). Long-term stability remains to be tested.  Results from Giano, as well as the implications for Nahual, will be presented within other talk this meeting.  Same idea (to adapt the Giano’s cryogenics concept) is being considered by the Spirou’s team (at the Observatoire Midi- Pyrénées)‏

17. Área de Instrumentación F. Javier Fuentes Instituto de Astrofísica de Canarias 17 Cryogenics concept. Design status (I)‏  LN2 will be an integral part of the optical bench to guarantee a close contact between LN2 and the bench surface.  LN2 temperature will be maintained stable by controlling the pressure of the N2 boiling gas down to 1 mbar (TBC)‏  Detailed concepts of the cold shield (to attain an isothermal environment in the optical bench) and the intermediate shield (or shields), using thick aluminium plates and MLI blankets (10 to 30 layers), will be presented in this meeting.

18. Área de Instrumentación F. Javier Fuentes Instituto de Astrofísica de Canarias 18 Cryogenics concept. Design status (II)‏  A detailed steady-state thermal model, predicting a density of radiation better than 0.8 W/m 2, has been developed for this configuration.The model will be presented and commented within other talk this meeting. Proposals to avoid hot-spots will be also presented.  A vibration-free pulse-tube cooler will be used, if needed, to cool the detector and the vacuum getter (down to 10 K)‏

19. Área de Instrumentación F. Javier Fuentes Instituto de Astrofísica de Canarias 19 Cryogenics concept. Giano design

20. Área de Instrumentación F. Javier Fuentes Instituto de Astrofísica de Canarias 20 Cryogenics development  A collaborative framework is under discussion between the interested groups (presently Arcetri, IAC and UL) to share the tasks to design, manufacture, integrate and test a cryostat for Nahual. This will allow to identify the final temperature stability that can be reached with the Nahual configuration during long periods of time (as requested in the science requirements).  The private companies involved in the design and manufacturing of Giano (Studio Tomerelli and Criotec Impianti) would participate in the development of Nahual cryogenics as far as it is possible.  The schedule and detailed task sharing will be discussed during this meeting.

21. Área de Instrumentación F. Javier Fuentes Instituto de Astrofísica de Canarias 21 Support Trusses concept  The following alternatives are being studied for the trusses supporting the cold bench:  Giano’s isostatic hexapod  Same concept, but using flexures/flexural pivots at the interfaces  G-10 isostatic or hyperstatic supports. Flat plates of cylinders  Use of titanium instead of stainless steel  A detailed analysis of alternatives will be presented within other talk this meeting

22. Área de Instrumentación F. Javier Fuentes Instituto de Astrofísica de Canarias 22 Cryogenic wheel mechanisms  Wheel design could be based on proven concept from existing instruments

23. Área de Instrumentación F. Javier Fuentes Instituto de Astrofísica de Canarias 23 GTC Nasmyth envelope compliance