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MOSFIRE Multi-Object Spectrometer For Infra-Red Exploration

Update on MOSFIRE multi-object spectrometer for Keck 1 Cassegrain focus, highlighting design requirements, project status, achieved milestones, and challenges. Details on rotator module, dewar assembly, CSU status, optics, cryo-mechanisms, and detector head focus.

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MOSFIRE Multi-Object Spectrometer For Infra-Red Exploration

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  1. Update presentation to the WMKO Science Steering Committee Ian McLean, Chuck Steidel, Sean Adkins November 3, 2008 MOSFIREMulti-Object Spectrometer For Infra-Red Exploration

  2. Cassegrain focus of Keck 1 Wavelengths: 0.975-2.40 m Resolving power (R) > 3,200 for a slit width of ~0.7 (2.9 pixels) Optics allow up to 46 x 7.0 slits over entire 6.14 x 6.14 FOV Imaging field of 6.8 diameter projected onto a 6.14 square 2K x 2K HgCdTe detector with 0.18 pixels; 5e- noise Cryogenic Slit Unit (CSU) reconfigurable under computer control without thermal cycling in < 5 mins. Independent CCD Guider Cost-capped project ($12.3M) Summary of Design Requirements Arguably, most challenging IR instrument to date.

  3. Summary of Project Status • Significant progress since June 2008 • Several challenging problems resolved • Major milestones achieved • MOSFIRE is now in Integration & Testing (Year 4) • On-target for first cool down early December 2008 • Running ~6 months behind original DDR schedule • Still within budget, but remaining contingency tight • Outstanding team; successful joint operation among CIT, UCSC, UCLA and WMKO

  4. Milestones Achieved • Rotator module aligned at Keck I Cass, delivered to CIT, installed in modified ESI stand and now in use for I&T • Dewar shell & internal structure pumped and baked out; MLI, CCRs, thermal wiring & dummy camera installed • CSU complete; ready for cryogenic testing at CERN • Lens coating issues apparently resolved: 10 of 13 science optics delivered to UCLA; all other optics (guider, folding flats, windows, grating & filters) in hand; lens mounting procedures refined • Mechanisms (Grating, Pupil, Filter, Flexure Compensation) built; all pass warm tests; detector focus mechanism in fab • Science grade detector received; ASIC-driven engineering grade detector achieves <6 e- rms with Fowler Sampling Some details follow …

  5. Rotator Module • Rotator Module • Built by UCO/Lick • Aligned on Keck 1 • Received at CIT and installed in modified ESI stand • Drive system installed by UCO/Lick • In use for instrument assembly and test

  6. Dewar Assembly • Dewar assembled with internal structure (Bulkheads A & B) & laminate thermal stand-off tube • Pumped down: trapped water and other contaminants found • Initiated a long (6 weeks) vacuum bake out with cold trap and residual gas analyzer - successful

  7. Dewar Vacuum Testing • Finally reached ~1E-5 Torr at room temperature • Contaminant identified • JPL lab analyzed sample of “goo” found in cold trap as part of a “common lubricant” • Source of contamination found during disassembly: • Insufficient cleaning to remove cutting fluid from front barrel shield at weld joints & pockets for cable penetrations • Insufficient cleaning of laminate tube HeliCoil inserts to remove grease used for assembly • All parts successfully re-cleaned at CIT

  8. Installation of MLI and CCRs • Multi-layer insulation (MLI) has now been added • Subcontract to SDL • Thermal straps for CCRs installed • Dummy camera with cross hairs installed • Thermal wiring (temperature sensors and heaters) installed • CCR Heads (pair) being installed now

  9. CSU Status • The CSU is fully assembled and undergoing acceptance testing • Warm tests meet specification • Horizontal position • Vertical position • Ready for cryogenic testing at CERN (this week) • We are sending a computer to enable remote testing of the operation of the MOSFIRE CSU server with the CSU controller software (this month) • Due: late December/early January

  10. Optics Status • Warm optics complete • guider doublets bonded (all at CIT) • Science optics in coating • 10 lenses coated & shipped to UCLA • Typical reflectance <0.6% per surface from 0.97-2.40 m • As-built grating and filters meet spec • QC problems at coating vendor seem to be resolved • Poor adhesion due to improper cleaning • Regrinding & polishing done; 3 lenses left to coat or recoat • Cryo-testing of lenses in progress

  11. Grating Shim Proximity Sensor Cryo-Mechanisms • Grating turret with dummy mirror and dummy grating; proximity sensor installed for testing; cryo-motor installed • Excellent preliminary results on warm test repeatability of this mechanism 0.04-0.06 pixels(0.1 pixels was goal)

  12. Cryo-Mechanisms • Pupil Mechanism • Warm testing complete • Filter Wheel • Warm testing resumed • Flexure Control mechanism • Warm & Cold testing complete • Detector Head Focus mechanism • Prototyped; final unit in fab

  13. Science Detector Initially 4 devices; accepted M2; then Teledyne made M5 and gave us the opportunity to switch!

  14. MOSFIRE 5: 2μm Flat/QE map 88±2% QE

  15. ASIC Tests on Eng. Grade 32-channel readout by ASIC Engineering Grade Device Observed Predicted

  16. Status – Electronics/Software • Electronics • On schedule for 1st & 2nd dewar integration milestones • Thermal circuits now installed for first cool down • Glycol cooling for Electronics Cabinet in fabrication • Software • All GUIs in advanced state of development • Hardware servers almost complete, including CSU • Deliverable computers received • Test routines running mechanisms

  17. Remaining Risk • Optics is highest risk now • 3 of 13 lenses left to ship • Cryo testing for coating adhesion in progress • Lenses must be aligned and bonded into their cells • Significant effort on-going to refine alignment and bonding procedures • Careful review and rehearsal prior to optics mounting is continuing • 3D metrology at every step using CMM • Dewar • First cool down will identify any thermal performance issues • Mechanisms • All will be cryo-tested prior to installation • Find and correct problems without major impact to schedule • CSU will be cold tested (at CERN) prior to delivery • Expected delivery late December or early January • Installation scheduled for March 2009 Risk Status Matrix follows …

  18. MOSFIRE Risk Status Orange highlighting flags highest risks

  19. MOSFIRE Schedule Current schedule has been holding.

  20. Budget Summary • Budget • Cost cap = $12.3M ($11.2M + $1.1M contingency; 10% materials, 15% labor; 4.5 project years) • Current estimated cost-at-completion $11.7M • Still within available funding, but significant risk remains • Current budget includes effect of 6 month slip • Anticipated contingency usage • Fabrication cost over-runs • CSU cost overrun (shared with CSEM) • Based on anticipated I&T monthly labor costs of ~$38K per month, funding is available for ~9 months additional labor beyond current First Light date of March 31, 2010

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