NGAO System Design Phase Update Peter Wizinowich, Rich Dekany, Don Gavel, Claire Max for NGAO Team (with input from Sean Adkins, Matthew Britton, Ralf Flicker, Chris Neyman) SSC Meeting June 20, 2007

2 Presentation Sequence Project Report #3 Science & System Requirements System Engineering –Performance Budgets –Trade Studies –System Architecture Keck Science Meeting Summary

Project Report #3

4 3 rd report submitted to Directors on June 18 Emphasis during this report period has been on: –Scheduled mid-year replan Replan complete & being tracked –Science case & system requirements Good progress on system requirements & significant work remains Postdoc, Elizabeth McGrath, has started on a part-time basis –Performance budgets & trade studies Astrometry & wavefront error reports issued Good progress on companion sensitivity 9 trade studies complete –The definition and start of the system architecture phase Priority task for this summer

5 Replan Replan documents (v26) posted at –KAON 481 System Design Phase Mid-FY07 Replan –MS Project plan –Excel spreadsheet which records the changes Purpose to accomplish what we need for the system design phase within remaining budget & schedule. Endeavored to utilize lessons learned from the 1 st 6 months. –Descoped some activities not critical to system design –Added some new activities that have been identified from our studies –More encompassing system architecture phase introduced prior to subsystem designs –Different management approach selected - using a small dedicated team with weekly telecons, for the 3 month system architecture phase. This phase will act as a test of this approach. In addition we will need to actively work with the team to bring tasks to closure

6 Replan WBS 1 SD Phase Management Minor changes WBS 2.1 Science Requirements. All science cases initially scheduled to be completed by 4/30/07 1 to 7 month slips with 8/30/07 completion Cancelled “Galactic Center Nature of Sgr A*: 3-5 µm color & 2 µm polarimetry variability” case due to relatively low priority Science Case Requirements Document v2 slipped by 3 months. v3 by 2 weeks. v4 unchanged. WBS 2.2 Observatory Requirements & 2.3 System Requirements. System Requirements Document v2 slipped by 2 months. v3 by 2 weeks WBS Performance Budgets. 1 of 8 budgets scheduled for completion by 3/30/07 completed Completion dates for these 7 budgets slipped by 2 to 8 months

7 Replan WBS Trade Studies. 29  19 trade studies 9 of 21 trade studies scheduled for completion by 3/30/07 completed 3 trade studies slipped by 1 to 6 months 12 trade studies cancelled: –K&L-band science. L-band low priority & K-band covered in background performance budget. –Instrument balance. More of an Observatory issue. –AO enclosure temperature. Better to understand system architecture 1 st –Dichroics & beamsplitters. Cost & feasibility largely associated with optics size –Slow WFS. Adequate information from the Keck experience. –Centroid anisoplanatism. Not a significant design driver. –Deformable mirror stroke requirement. This does not appear to be a limitation. –Stand-alone vs DM on TT stage. Preliminary evaluation deemed adequate. –Correcting fast TT with DM. Already cancelled. This will be part of our baseline. –Focus compensation. Largely understood from the Keck (and other) experience. –Laser pulse format. Already largely covered on the LAO sodium laser web page. –Free space vs fiber. Already being done for K1 LGS. 2 trade studies added: –Deployable IFU & low order wavefront sensor AO & object selection. Previously part of D-IFU instrument study. Need system design for this & to understand object selection options –Uplink compensation. Could significantly reduce required laser power.

8 Replan WBS System Architecture. Significantly restructured & rescheduled. Substantially more labor (6 person core) Other areas reduced where work now addressed in this WBS WBS 3.2 AO System. Reshuffling of personnel & dates Two new tasks: 1) atmospheric profiler & 2) d-IFU & LOWFS AO & Object Selection WBS 3.3 Laser Facility. Reshuffling of personnel & dates WBS 3.4 Science Operations. PSF reconstruction task added WBS 3.5 Science Instruments. Significantly restructured & rescheduled Requirements & definition WBS added Visible & near-IR imagers grouped, as were the visible & near-IR IFUs Thermal NIR imager previously dropped due to lower priority. WBS 4 System Engineering Management Plan. Relatively minor changes Budget & Personnel Changes. Postdoc starts 8/20/07 in terms of funding (actually start 3 days/week in late May) No students used so far. Reduced 1850 hrs by 2/3rds Considerable amount of personnel leveling & task redistribution

9 Project Report #3 – Status of New Milestone Dates #MILESTONEDATESTATUS 1SD SEMP Approved10/9/06Complete 2SD phase contracts in place10/27/06Complete 3Science Requirements Summary v1.0 Release 10/27/06Complete 4System Requirements Document (SRD) v1.0 Release 12/8/06Complete 5Performance Budgets Summary v1.0 Release 6/15/0725% complete 6SRD v2.0 Release5/22/07Good progress 7Trade Studies Complete6/22/0715 of 18 complete 8SRD v3.0 Release 9/7/07 9System Design Manual (SDM) v1.0 Release 9/21/07Some work as part of system architecture 10Technical Risk Analysis V1.0 Release 9/21/07Some work as part of system architecture 11Cost Review Complete12/7/07Some work as part of system architecture 12SDM v2.0 Release 2/12/08 13System Design Review Package Distributed 3/4/08 14System Design Review3/31/08 15SDR Report & Project Planning Presentation at SSC meeting 4/14/08

10 Project Report #3 Schedule: 38% of System Design Phase activities complete through May Budget: $427.5k spent through May. –52% of the FY07 budget (versus plan of ~67%) –41% of the System Design Phase budget, excluding contingency

11 Project Report #3 Products since last report include the following KAONs: –303 Mauna Kea Atmospheric Parameters –471 Wavefront Error Budget –474 Photometry for NGAO –475 Tomography Codes Comparison and Validation for NGAO –476 Observing Models Trade Study –480 Astrometry for NGAO –481 System Design Phase Mid-FY07 Replan –482 Keck Telescope Wavefront Error Trade Study –483 Keck Interferometer Support Trade Study –485 Adaptive Secondary Mirror Trade Study –487 LOWFS Architecture Trade Study –490 Rayleigh Rejection Trade Study –492 Null-mode & Quadratic Mode Tomography Error –493 Science Instrument Reuse Trade Study –494 NGAO Project Report #3 All KAONs at

Science Case Requirements + Science Instruments

13 Science Case Requirements Review of the science requirements section of the System Requirements Document (SRD) raised issues –Need to complete science requirements for each science case –Need to document flow down to performance requirements –Science Case Requirements Document (SCRD) v1 missing several science cases –Need to better document science operations requirements & flow down Next steps –Complete identification of performance requirements for AO & instruments –Work on “TBD” parameters identified in SRD –Complete science operations requirements section with identification of AO & instrument requirements –Complete SRD v2 with goal values for performance requirements & initial sections for implementation & design requirements

14 Science Requirements: Improved Methodology Cleaner separation between science-based requirements and derived requirements for AO + instruments Example: Spectroscopy of galaxies lensed by galaxies (3 of 17 rows) Better basis for evaluating AO trades (in process)

15 Science cases have been re-worked using new approach “Science” parts of science requirements are clear Flow-down to AO & instrument requirements in process To date, no science case requires corrected fields larger than arc sec However, analysis of an additional science case is needed: resolved stellar populations –Trade-off between lower Strehl ratio over larger contiguous area (MCAO), vs. higher Strehl over multiple smaller areas (MOAO) Until this is resolved, the system architecture study is carrying along one MCAO option

16 Science Case Requirements The cases with initial science requirements tables include: –Asteroid companions survey and orbit determination –Moons of the giant planets –Shape and size of asteroids –Galactic Center astrometry and radial velocities –Planets around low mass stars –High redshift galaxies –Nearby AGNs –Gravitational lensing –QSO host galaxies Galactic Center Nature of Sgr A*: 3-5 µm color & 2 µm polarimetry was descoped as lower priority in the replan. The science cases still requiring initial requirements tables include: –Debris disks, protostellar envelopes and outflows: contrast and polarimetry –Resolved stellar populations in crowded fields V1.10 of SRD:

17 Science Instruments (IWG) Working on initial flow down from science requirements Draft of “Summary Descriptions of NGAO Instruments” in progress Next step is review of instrument function allocations and descriptions with science team

NGAO System Engineering: Performance Budgets Trade Studies System Architecture

Wavefront Error Budget Predictions Assumes a typical Mauna Kea turbulence profile with a Greenwood Frequency of 41 Hz Optimum system configuration depends on observing scenario Frame rates up to 2.5 kHz Asterism diameters up to 1.6 arcmin

20 Astrometric Precision Recommendations Astrometric accuracy/precision limited by imperfect PSF, optical distortion knowledge & refraction effects. Several tools could improve astrometry: C n 2 measurement on minute timescales –Baseline to understand stability expectations –Aid to target selection & observing strategy decisions –Profiles in post-processing algorithms for improving astrometry Auxiliary PSF camera –To provide simultaneous OTF for use in post-processing –Nyquist sampled & deployable to find a PSF Ability to solve for & monitor optical distortion in AO & instrument –Example: a well-machined pin hole slit mask far upstream in the optical path –Need to rotate & translate to solve for positions & optical distortions Atmospheric dispersion corrector (ADC) –Could make identifying & correcting residual atmospheric refraction more difficult Provide plate scale stability at level of current Keck AO (<10 −4 over a night) Provide an adequate wavefront error –Preliminary: 140 nm required to achieve < 0.1 mas

21 Trade Studies The following studies have been completed since the last meeting: –MOAO & MCAO –Adaptive secondary mirror option –Keck Interferometer support –Science instrument re-use –Telescope wavefront errors –Observing model –Rayleigh rejection –LGS wavefront sensor number and type –Low order wavefront sensor architecture Remaining studies: –Optical relay & field rotation strategy –D-IFU & LOWFS AO & object selection (new) –Uplink compensation (new)

22 LOWFS architecture Trade Study Main conclusions: –Benefit from doing LOWFS in the NIR & combining J+H band Consistent with KAON 470 –Pyramid overall performance better than Shack-Hartman (not significantly for tip-tilt) –NGS image sharpening is a performance driver: Strongly suggests internal MEMS correction Consider dedicated LGS for NGS sharpening Tentative architecture recommendation: –Two near-IR tip/tilt WFS –One 2x2 pyramid WFS (tip/tilt, focus, astimatism) –All three have internal MEMS DMs

23 System Architecture Focused “core” team (6 members) Builds on work to date (requirements, performance budgets & trade studies) 1 st define 2-3 candidates for each of the key subsystems: –LGS production & control, optical relay, LGS & NGS wavefront sensing, acquisition –Example - LGS WFS evaluation includes: radial & conventional Shack-Hartman WFS & Pyramid WFS 2 nd evaluate these options for performance, risk & cost July 9-13 UCSC meeting will focus on: –Candidate architectures as combinations of top ranked subsystems –Architecture system-level cost estimation –Initial subsystem functional requirements

24 Keck Science Meeting We would like to request part of the Keck Strategic Planning Meeting for NGAO –Entire morning or afternoon if possible Goal –Broader community exposure, input & engagement Suggested Topics –Science cases & requirements –System design overview –Operational models –Science instruments

25 Summary Management: –Scheduled mid-year replan completed –Keeping on schedule will need close attention –Intention continues to be to deliver the system design within budget & schedule Technical: –Good progress made on requirements, performance budgets & trade studies –System architecture phase begun