1 / 49

“Infrared Spectroscopic Imaging Survey (IRSIS) payload for an Indian Satellite”

(1 st Indo-French Meeting, 04-Dec-2007). “Infrared Spectroscopic Imaging Survey (IRSIS) payload for an Indian Satellite”. S K Ghosh on behalf of IRSIS team ( TIFR, IUCAA, PRL, IIA, ARIES, Paris Observatory, IAS-Orsay ).

zeno
Download Presentation

“Infrared Spectroscopic Imaging Survey (IRSIS) payload for an Indian Satellite”

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. (1st Indo-French Meeting, 04-Dec-2007) “Infrared Spectroscopic Imaging Survey (IRSIS) payload for an Indian Satellite” S K Ghosh on behalf of IRSIS team (TIFR, IUCAA, PRL, IIA, ARIES, Paris Observatory, IAS-Orsay)

  2. Motivation & Scientific objectives for the IRSIS Proposal : -Exploit the crucial gap in astronomical spectroscopic capability in the wavelength range 2 - 6 micron (left between HST-NICMOS cut-off & SPITZER-IRS cut-on) -Being unexplored ‘territory’, enormous science potential even with an experiment with limited capabilities (i.e. limited sophistication & resources); - Need for Space borne experiments (Earth’s atmosphere : transparency, background)

  3. Primary science goals : Spectroscopic Survey at 1.7-6 mm covering > 50% of the full sky (within 2 years) including the Galactic plane ; (i) Detection of several spectral lines & features from the Interstellar Medium (ISM) of our Galaxy (inaccessible from ground); (ii) Spectra of stars in our Galaxy and nearby galaxies; (iii) Complete census of Low Mass objects in the Solar neighbourhood (~ 30 pc).

  4. Large volume of quantitative details leading to much better understanding of energetics & composition of the Interstellar Medium; • Infrared characterization of (1) stars, and (2) various types of Solar system bodies.

  5. Indian InfraRed Spectroscopic Imaging Survey (IRSIS) Scientific Objectives #1 • Interstellar gas in the Galaxy (+ LMC, SMC, M31) : • mapping the Galactic Plane in • - PAH bands at 3.3 & 6.2 mm (1.68 mm harmonic), • size distribution from relative strengths; PAD at 4.2 mm; • - recombination lines : • Paschen-a (20% of Ha), Brackett-a (10%) ; • - ro-vibration bands of molecular H2, HD ; 2) Interstellar & circumstellar solid matter : - very small grains (nanodiamonds from 5 mm feature) ; - signatures of hydration of silicates (in absorption) ; - elongation vib modes of isolated OH (2.6-2.9 mm) - carbonaceous matter ; - distribution of interstellar ices (H2O @ 3.07 mm, CO2,CH4), ISM  primitive solar nebula (Comet formation) ;

  6. Indian InfraRed Spectroscopic Imaging Survey (IRSIS) Scientific Objectives (continued …) #2 3) Stellar populations in the Galaxy (classification) : - precise study of evolved stars (giants, supergiants, PNe) - chemical composition (metallicity) - effective temperatures & luminosity classes (from CO & H2O indices) - stars with dense envelopes (H2O & NH3 ices @ 3.1mm) - emission line objects (Be star, proto-planetary nebulae, Fe II lines, PAH bands in post-AGB nebulae, …) 4) Low mass stars in the solar neighbourhood : - complete census (dwarf stars : class M, L, T, brown dwarf characterized by molecular bands; e.g. CH4) - precise mass & age (using model)

  7. Indian InfraRed Spectroscopic Imaging Survey (IRSIS) Scientific Objectives (continued …) #3 5) Star forming regions : census of the nearby complexes (Taurus, Ophiucus, etc) complete up to ~ 10 Jupiter masses ; 6) Population of distant (z ~ 2-3) starburst galaxies (from limited deep survey, ~ 30 sq. deg.) : first generation stars  period of galaxy formation, (rest frame visible spectra shifted to IR) ; diffuse extragalactic background ; 7) Small bodies of solar system : ~ 3000 asteroids & comets, their mineral composition ; evolution of solar system ; 8) Unexpected discoveries from new survey … ??

  8. Important spectral lines in the 1.7-6 mm range inaccessible from the ground Wavelength (mm) Line identifier Type of target 1.87 Paschen-a stars / ISM 1.96 [Si VI] PN 2.41 H2 (1-0, Q(1)) ISM 2.63 Brackett-b stars / ISM 4.49 [Mg VI] PN 4.53 [Ar VI] PN 5.61 [Mg V] PN

  9. Important spectral bands in the 1.7-6 mm range inaccessible from the ground Wavelength (mm) Line identifier Type of target 1.8 C2 Carbon stars 1.9 H2O M stars 2.4 CH4 Brown Dwarfs 2.7 OH in Silicates ISM 3.05 Ice (H2O) ISM 3.1 C2H2, HCN Carbon stars 3.3 PAH (in emission) ISM 3.5 nano-diamonds stars 4.2 Ice (CO2) ISM 4.6 CO M/C Stars 5.2 C3 Carbon stars 6.0 Ice (H2O) ISM 6.2 PAH (in emission) ISM

  10. Examples of typical spectra : (rich !) Cushing et al (2006)

  11. Example of topicality : Comparison between measurements ( ) and theoretical models ( , ) (R ~ 200) (M2 super-giant) Tsuji (2006)

  12. “Quality” of the Atmospheric Windows in the Near & Mid Infrared (#1) (Kitt Peak; 2080 m; “best condition”) J H K 1.0 0.5 Transmission 2.6 1.0 1.4 2.2 IRSIS coverage Wavelength ( mm)

  13. Atmospheric transmission …. (continued #2) (… at Mauna Kea; 4200 m) L’ 1.0 0.5 Transmission 3.2 3.6 4.0 4.4 Wavelength (mm) IRSIS

  14. Atmospheric transmission … (continued #3) (… at Mauna Kea; 4200 m) • emissivity  background M 1.0 0.5 Transmission 4.2 5.4 Wavelength (mm) IRSIS

  15. Atmospheric transmission … (continued #4) (… at Mauna Kea; 4200 m) N Q Transmission 1.0 0.5 6.0 10 14 22 IRSIS coverage 28 Wavelength (mm)

  16. Atmospheric Backgrounds : affecting ground based observations - - atmospheric “fluorescence” : AIRGLOW; OH- originates at ~ 100 km ; spatial & temporal variation too ! limits photometric accuracy ; • at l > 2.3 mm, dominated by thermal emission • (230-280 K; peak ~ 12 mm) ; • + emissivity of the telescope ; • - scattered moonlight

  17. Infrared background at the ‘best’ site (Mauna Kea) (comparison with space platform) @ 4,200 m Jy/(sq. arc-sec) M K L IRSIS COBE

  18. We just saw – Infrared astronomy (near/mid IR) from Space : has many advantages over Ground based ; (access to uninterrupted wavelength range; lower background, not varying with time ; etc) Matured Satellite Platform/(s) available to us (Indians) ! (Courtesy : ISRO) BUT, what is the international scene (competition) ?

  19. Perspective vis-a-vis international scene

  20. Given the international scene, is there a niche for Indian astronomers ? Yes ! - Exploit ~ 2-6 mm gap in Spectroscopic capabilities between IRS/Spitzer & NICMOS/ HST !! - ASTRO-F is unsuitable for Spectroscopic Survey covering large fields ; • Concentrate on Spectroscopic Survey with emaphasis on features / lines inaccessible from the ground ; Major strength : - Large sky coverage (Survey) with Spectroscopic dimension ! - simultaneous capability of Spectro-photometry of ‘point’ as well as ‘extended’ sources !

  21. Technical feasibility ? What are the major Technological challenges for realizing an Infrared spectrometer (~1.7-6 mm ) with R ~ 100 ? - cryogenics (achieving ~ 80 K in Low Earth Orbit, Earth’s albedo) provenspace grade cryo-coolers now (2004+) available commercially ! - space grade detector arrays with ‘astronomy’ grade performance; ~ 80 K operation ? recent developments from JWST efforts ! - fibers with transmission in 1-6 mm new materials developed in France !

  22. Summary of the proposed instrument (IRSIS) #1: Wavelength coverage : 1.7—6.5 micron Sky coverage : > 50%, including Galactic Plane Angular resolution : 18” Spectral resolution, R = (l/Dl) ~ 100-120 Survey Sensitivity (3-s; 10 sec) – Point source : @K (2.2 mm) = 14 mag. Diffuse emision : SW (1.7-3.4 mm) ~ 0.4 MJy/Sr LW (3.2-6.5 mm) ~ 1.5 MJy/Sr Confusion limit : 2,500 stars/sq. deg.

  23. Summary of the proposed instrument (IRSIS) #2 : Medium size telescope : ~ 30 cm (dia) @~120K Instantaneous FoV : 15’ x 15’ (9 sub-fields - 5’x5’, each feeding one slit) Micro-lenses + Infrared fiber-bundles couple Focal Plane to multiple slits of 2-channel spectrometer : Channel SW : 1.7—3.4 mm; Channel LW : 3.2 – 6.5 mm; Optical components for dispersion (Grating) Cooled (~ 80 K) detector arrays : 1024x1024 HgCdTe (x 2)

  24. IRSIS : Basic Specs -

  25. Typical expectations from IRSIS : • -Typical number of stellar spectra detected : • ~ 2,000 per sq. degree (@ Galactic lat., b ~ 0 deg. • ~ 500 per sq. degree (@ b ~ 45 deg. • -Detection of 3.3mm PAH feature from the • Galactic Plane with S/N ~ 100 (10 sec. int.); • Number of L-Dwarfs discovered & • classified : ~ 2,500; • -Number of Asteroids & Comets with • detected spectral features : ~ 3,000;

  26. Block diagram of IRSIS

  27. Spectroscopic Imaging : Topology - Telescope focal plane  Slit  detector array Simultaneous spectra from all sub-areas (fibers) of sky !

  28. Concept from MUSE instrument (ESO-VLT)

  29. Exploring 1-degee of freedom (telescope moves, spectrometer fixed to S/C deck) Very deep exposures for selected targets possible;

  30. IRSIS with one degree of freedom : ?? (NOT TO SCALE)

  31. Target low-power cryo-cooler with space heritage (K508 from M/s RICOR) (220mW load @ 77 K) Mass : 450 gm Size : 70-120 mm Power : 7 W (steady) 17 W (max) MTBF : 10,000 hrs (Used in MMM payload of Chandrayaan-1)

  32. Choice of Detector Arrays : Tunable cut-off wavelength (3.4 & 6.5 mm)  HgCdTe (MCT) FPAs Ultra-Low Dark Current at ~ 80 K Exciting recent developments related to James Webb Space Telescope (JWST) useful ! Development of MBE process for successful fabrication of larger format arrays (upto 2048 x 2048) Development of a powerful ASIC for driving the array and signal processing (SIDECAR), operational at cryogenic temperatures (30 K to RT)

  33. Liquid Phase Epitaxy (LPE)  Producible Alternative to CdTe for Epitaxy (PACE) PACE-1  Sapphire substrate Molecular Beam Epitaxial (MBE)

  34. Drastic reduction in Dark Current for MBE -

  35. Identified Detector array : HAWAII-1RG ‘R’  Reference columns : Insensitive to temperature variations;

  36. Big saving in Mass, Power; EMI/EMC

  37. (ASIC cost ~ Rs. 200 Lakh!) DETECTOR ASIC

  38. ASIC - SIDECAR : System Image Digitizing, Enhancing, Controlling And Retrieving Fully software controlled selectable Read-Out scheme ! 22 mm x 15 mm 30 K  RT < 0.1 Watt

  39. Orbit & Spacecraft specs - 900 km Polar Sun-synchronous Inertial, 3-axis stab. (L2 ?)

  40. Mass budget -

  41. Raw Power Budget -

  42. Proposed plan for implementation (institutional responsibilities): a) TIFR : Overall system configuration, Telescope optics, Thermal (Passive/active Cooling), Detectors, Mechanical Structures, Data Handling, Interfaces with the Spacecraft-bus; b) IUCAA : Fiber optic system design; c) PRL : Optical design /development of Spectrometers; Ground based follow-up; d) IIA : Off-line data processing pipeline software; e) ARIES : Data analysis; e) Paris Observatory + IAS-Orsay: Micro-lenses; Cryogenic Infrared Fibers (Anamorphoser)

  43. Important components :

  44. Realization strategy :

  45. Status & Plans : ISRO’s Announcement of Opportunity (AO) : March 2006 Proposal Deadline : July 31, 2006 (IRSIS version #1) TIFR review (XI Plan) : September 2006 Results of ISRO Review #1 : November 2006 (suggested improvements) IRSIS version #2 : January 2007 IRSIS-ISRO Technical meeting : March 2007 IRSIS version #3 : April 2007 Results of ISRO Review #2 : August 2007 (Phase 1 support : 2 years for Engineering Model) Next actions : Detailed Project Report (DPR) by December 31, 2007 Baseline Design Review (BDR) ~ February 2008 ? Preliminary Design Review (PDR) ~ end-2008 ??

  46. Thank you !

More Related