NGAO System Design Phase Update

1
NGAO System Design PhaseUpdate

• Peter Wizinowich, Rich Dekany, Don Gavel, Claire
  Max
• for NGAO Team
• SSC Meeting
• January 24, 2007

2
Presentation Sequence

• SSC Co-Chair Questions
• Management Update
• Management Structure
• Systems Engineering Management Plan
• Documentation Coordination
• Instruments Working Group
• Project Report 1
• Technical Update
• Science Requirements
• Performance Budgets
• Trade Studies
• Summary

3
SSC Co-Chair Questions

• All of the following questions are addressed in
  the Systems Engineering Management Plan
  (summarized in the following Management update
  slides)
• What is the product of this study phase?
• Following Keck development process (see System
  Design phase deliverables on slide 6). Includes
  conceptual design (with options), initial cost
  estimate management plan for remaining project.
  Instrument concepts developed to proposal level
  (precursor to their System Design phase).
• Are any intermediate reviews planned?
• Frequent internal product reviews, including cost
  reviews in Aug Dec. SDR at end of this phase
  (3/31/08). Project reports provided prior to
  each SSC meeting.
• Who is doing what, and what of time is each
  person devoting to NGAO?
• Details in project plan. High level summary of
  key personnel on slide 10.
• What are the major goals/milestones of this
  phase?
• See milestones on slide 9.

4
SSC Co-Chair Questions

• What are the big issues and how are they being
  addressed?
• Big picture Cost, schedule performance
  structuring the program to suit the funding.
  Science engineering team working closely with
  management to produce a compelling realistic
  vision.
• Near term Science community input team
  ramp-up. Engaging scientists in science case
  requirements performance budgets. Freeing
  personnel from other responsibilities.
• What is the timescale for this phase and when can
  the SSC expect a full report?
• See schedule on slide 15.
• What is the relationship between the NGAO team
  and the AOWG
• AOWG Bouchez, Dekany, Koo, Larkin, Liu
  (co-chair), Macintosh, Marchis, Matthews, Max
  (co-chair) Ellis (rotating on)
• The AOWG was a very active participant in the
  NGAO proposal.
• Max, Liu Marchis are leading the science case
  requirements
• AOWG last met 8/06.
• Comparison of NGAO versus planned AO performance
  of current generation. Why should we believe new
  models?
• Addressed in the performance budgets section.

5
A. Management Structure

• Proposal approved at Jun/06 SSC Board meetings
• WMKO, UCO COO Directors subsequently
  established an Executive Committee (EC) to manage
  System Design phase
• Wizinowich-WMKO (chair), Dekany-Caltech,
  Gavel-UCSC, Max-UCSC, CFAO (project scientist)

6
B. Systems Engineering Management Plan (SEMP)

• SEMP submitted to Directors at end of Sept/06
• Verbal approval received to proceed
• Budget approval being finalized
• System design started Oct/06
• Completion planned for mid-FY08
• Products of this study phase (Q1) - System design
  phase deliverables
• System Requirements Document - Science
  Observatory requirements flow down to system
  requirements
• System Design Manual Performance budgets,
  functional requirements, system subsystem
  architectures
• SEMP For remaining NGAO phases
• System Design Report Summary for System Design
  Review

7
B. SEMP Approach

• Initial focus on requirements performance
  budgets to ensure that we understand largest
  levers on the design
• Initial attempt at defining the AO system
  architecture the functional requirements for
  the major systems
• In parallel with 1 2 perform trade studies to
  better understand the appropriate design choices
  
• A process of iteration and refinement will lead
  to the final version of the AO architecture
  major systems requirements
• Includes continued development of performance
  budgets functional requirements
• Develop cost estimates plans for remainder of
  NGAO project

8
B. SEMP Budget
163k increase in cost of labor since proposal,
due to distributed project nature Total work
same as in original proposal
9
B. SEMPMilestones
10
B. SEMP Team
Represents 84 of the work force.
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C. Documentation Coordination

• NGAO Twiki site at http//www.oir.caltech.edu/twik
  i_oir/bin/view.cgi/Keck/NGAO/WebHome
• Includes collections for
• Team meetings
• Agendas documents posted in advance action
  items posted followed up
• Executive committee
• Planning tracking documents
• EC weekly meeting minutes
• Work packages
• Table of WBS elements, planning sheets products
• Performance budgets
• Meeting summaries products
• Science team

12
D. Instruments Working Group

• Instruments Working Group (IWG) being formed for
  NGAO System Design Phase
• Focused on instrumentation related matters
• Instrument specialist perspective for NGAO
• Resource for AO system design team on
  instrumentation issues
• Organization (6 to 8 members)
• 3 to 4 funded from current NGAO plan
• Responsible for most of technical work related to
  NGAO instrumentation WBS
• Sean Adkins (IWG chair, overall systems,
  detectors, electronics interfaces)
• Anna Moore (instrument generalist, optical
  mechanical)
• James Larkin/UCLA IR Lab staff members
  (instrument design, optical mechanical,
  cryogenics experience)
• TBD software engineer
• 3 to 4 TBD volunteers from NGAO science team
• Primary contacts with science team for instrument
  related science requirements
• Regular meetings will be held involving the
  entire group
• Additional assistance advice will be sought
  from the diverse base of the collective
  instrumentation technical resources at UC CIT

13
E. Project Report 1

• Directors requested written project reports
  prior to each SSC meeting
• 1st report submitted to Directors on Jan. 19
• http//www.oir.caltech.edu/twiki_oir/bin/view.cgi/
  Keck/NGAO/SystemDesignPhasePlanning
• Good progress made on initiating NGAO System
  Design phase on building up an effective team
• Emphasis to date, as planned, on understanding
  the major design drivers through a process of
  iteratively developing the science case
  requirements the performance budgets
• Work has begun on a number of trade studies in
  support of the performance budgets the future
  design choices

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E. Project Report 1
15
E. Project Report 1
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E. Project Report 1

• Budget
• 772k budgeted for FY07 in 5-year plan
• 110k spent in 1st quarter
• Low due to slower than planned ramp up of
  personnel
• Average of 4.3 FTEs
• Summary
• Good technical progress as you will see in the
  following slides
• Team and management processes now largely in
  place
• Expect the teams rate of progress to be close to
  the rate in the plan during the 2nd quarter

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E. Project Report 1

• Products include the following KAONs
• 415 TMT site monitoring data (restricted access)
• 416 Atmospheric sodium density from Keck LGS
  photometry
• 417 Sodium abundance data from MAUI Mesosphere
• 419 LGS brightness predictions vs results
• 420 Accessing the MK TMT seeing weather data
• 427 Variable versus fixed LGS asterism
• 428 Implications Requirements for
  Interferometry with NGAO
• 429 LGS asterism geometry size
• 452 MOAO versus MCAO trade study report
• 455 Science Case Requirements Document
• 456 System Requirements Document

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Science Case Requirements System Requirements

• Max, Ghez, Law, Liu, Lu, Macintosh, Marchis,
  Steidel
• Neyman, Wizinowich

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Science Requirements Process

• Approach
• Start from significant science case development
  in proposal
• Analyze limited set of these key science cases in
  order to understand and document the requirements
  on NGAO Instruments
• Begin with cases that stress AO design the most
  in multiple directions
• Progress to include more science cases
• Iterate 4 times with AO instrument requirements
• For each case, discuss
• Science goals, proposed observations, AO
  performance requirements, instrument requirements

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Science Requirements Performance Budget Process
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Science Case Requirements DocumentRelease 1
Contents

• JWST and ALMA capabilities
• Future AO capabilities of other observatories
• Key science cases and what they stress most
• Multiplicity, size, shape of minor planets
• High contrast, wavefront error, visible light
  performance
• Planetary brown dwarf companions to low mass
  stars
• High contrast
• General relativistic effects in the Galactic
  Center
• Astrometry and radial velocity accuracy
• Assembly and star formation history of high z
  galaxies
• Lower backgrounds, multiple deployable IFUs, sky
  coverage

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JWST capabilities

• Cryogenic 6.5-m space telescope, launch in 2013
• Higher faint-source sensitivity than Keck NGAO,
  due to low backgrounds
• Not diffraction limited below K band
• Primary mirror spec
• NIRCAM px scale 0.035, NIRSpec px scale 0.1
• Areas where Keck NGAO would complement JWST
• Spectroscopy _at_ spatial resolution better than
  0.1, ? 0.6 - 2 µm
• Imaging _at_ spatial resolution better than 0.07,
  ? 0.6 - 2 µm
• Multi-IFU spectroscopy

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Key science requirements Multiplicity, size,
shape of minor planets

• Minor planet formation history and interiors by
  accurate measurements of size, shape, companions
• Small, on-axis imaging field ( 3 arc sec)
• Relative photometry to 5, astrometry 5 mas,
  wavefront error 170 nm, contrast ?H ? 5.5 at
  0.5 arc sec
• Instruments
• Imaging visible and near-IR
• Near IR IFU spectroscopy 1.5 arc sec field
  still need to specify spectral resolution
• Observing modes non-sidereal tracking,
  lt10 minute overhead switching between targets,
  consider queue or flexible scheduling

Asteroid Sylvia and moons
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Key Science RequirementsPlanetary brown dwarf
companions to low mass stars

• Faintness of low-mass stars, brown dwarfs, and
  the youngest stars make them excellent NGAO
  targets
• Small imaging field 5 arc sec
• Relative photometry to 5, astrometry to PSF
  FWHM/10, contrast ?H 13 at 1 arc sec
• Instruments
• Imaging 0.9 - 2.4 microns
• Single near IR IFU spectroscopy, still need to
  specify spectral resolution
• Observing modes coronagraph needed

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Key Science RequirementsGeneral relativistic
effects in the Galactic Center

• Measure General Relativistic prograde precession
  of stellar orbits in Galactic Center
• Requires astrometric precision of 100 ?as (now
  250 ?as) and radial velocity precision to 10
  km/sec (now 20 km/sec)
• K band, wavefront error 170 nm
• Imaging field 10 x 10 arc sec
• Near IR IFU spectra, R 4000, FOV 1 x 1,
  need IR ADC

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Key Science RequirementsAssembly and star
formation history of high z galaxies

• Redshifts 1.5 z 2.5 most active star
  formation, form bulges disks
• Optical lines such as H? are shifted into near IR
• Density 2 - 20 / sq arc sec ? 6 to
  12 IFUs in field of regard
• J, H, K bands
• IFU fields 1 x 3 arc sec for sky subtraction,
  50 mas spaxels, R 3000 - 4000, EE gt 50 within
  50 mas for optimal tip-tilt stars
• Low backgrounds AO system lt 10-20 of
  (sky telescope)

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Science requirements summary to date

• Wavefront error 170 nm or better
• Need sensitivity study to see how science would
  fare if wavefront error were 200 nm
• Relative photometry to 5
• Contrast ?H ? 5.5 at 0.5 arc sec, ?H ? 13 at 1
  arc sec
• Astrometry companions to 5 mas, Galactic Center
  to 100 ?as. Need near-IR ADC.
• K-band backgrounds AO system IFU lt 10-20 of
  (sky telescope)
• Need sensitivity study to see how high-z science
  would fare at higher background levels
• Not yet found a compelling science case for a
  large contiguous field (i.e., MCAO)

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Instruments observing mode requirements, to date

• Instruments
• Refining the requirements developed for the
  proposal
• On-axis near-IR imager, field 10 x 10 arc sec,
  coronagraph
• On-axis visible imager (to 0.6 or 0.7 ?m), field
  3 x 3 arc sec, coronagraph?
• Near IR deployable IFU
• 6 - 12 channels, field of regard TBD
• Field of view 1 x 3 arc sec
• 50 mas spaxels, EE gt 50 within 50 mas for
  optimal tip-tilt stars
• Still need to evaluate optimum spectral
  resolution
• Observing modes
• Non-sidereal tracking, lt10 minute overhead
  switching between targets, consider queue or
  flexible scheduling

29
NGAO Performance Budget Development

• Dekany, Ghez, Marchis, Max, Liu, Gavel, Flicker,
  Wizinowich,
• Cameron, Lu, Britton, Macintosh, Neyman, Ireland,
  Olsen,
• Bouchez, Law, Bauman, Le Mignant, Johansson, Chin

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Developing Science-based Performance Budgets

• Systems engineering will consider all of the
  following budgets
• Model assumptions
• Model/tool validation
• Wavefront error vs. sky coverage for 5-7 science
  cases
• Photometric precision in crowded and sparse
  stellar fields
• Astrometric accuracy at the GC and in sparse
  fields
• High-contrast for diffuse debris disks and
  compact companions
• Polarimetric precision for high-contrast
  observations
• Transmission/background/SNR for several science
  cases
• Observing efficiency
• Observing uptime

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Performance Budget Development Goals

• Produce a technical report
• Describing the major drivers, including
  experimentally supportive information,
  quantitative background, and potential simulation
  results
• Produce a numerical engineering tool to support
  future design iterations
• Emphasizing abstracted quantitative scaling laws
  and interdependencies
• Support science requirements development
• Capturing the experience of the science team and
  reflecting quantitative underpinning to current
  limitations

32
Wavefront Error and Encircled Energy

• Science Cases
• Maintain all cases from the June 06 NGAO
  proposal
• Key Drivers for initial budget
• Uncertainty in tomographic reconstruction error
• Uncertainty in sodium laser photoreturn from the
  mesosphere
• Per delivered Watt, as a function of different
  pulse formats
• Requires 50W class lasers to investigate
  non-linear optical pumping effects
• Uncertainty in multi-NGS tilt tomography efficacy
• Not included in original budget development
• Uncertainty in tip/tilt control efficacy with
  large tip/tilt mirrors

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Wavefront error budgets

• For observations of
• TNO multiplicity
• Galactic Center
• Field galaxies
• Io
• Nearby AGN
• Gravitational Lenses
• During requirements flowdown initial design,
  all performance budgets will be used for rapid
  reevaluation of performance cost/benefit

Example for LGS observation of TNO using two
galactic M-dwarfs as tip/tilt stars
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Improving Performance Predictions

• Performance versus Blue Book
• Delivered system science instrument didnt
  achieve some requirements
• Environment different than some assumptions
• Why will NGAO performance estimates be better
• Experience at Palomar, Lick Keck
• Better understanding of Keck environment
• Performance estimation tools more complete
  anchored to actual performance
• For effects such as multi-guide star tomography
  for which we dont have real-world experience
• Based on modeling and detailed simulations
• Comparing validating these tools (TMT, Gemini,
  COO, Keck, UCO)
• Aided by lab experiments (e.g. LAO)
• Undoubtedly there will be real-world effects
  that we are not yet taking into account

35
Keck LGS AO Wavefront Error Budget
36
NGAO Trade Studies

• Dekany
• To date Bauman, Clare, Gavel, Flicker, Kellner,
  Neyman, Velur

37
Design Trade Studies

• Trade studies were initiated at the start of
  System Design phase
• We have completed or nearly completed
• Methods of mitigating laser Rayleigh backscatter
• Laser guide star asterism geometry
• Multi-Object (MOAO) Multi-Conjugate (MCAO)
  architectures
• Variable vs fixed laser asterism on the sky
• Fast tip/tilt opto-mechanical implementation
  options
• Low order wavefront sensor type number
• Additional design studies now underway include
• LGS wavefront sensor architecture type
• Science instrument re-use
• Telescope static dynamic errors
• Interferometer support
• Sodium return versus laser format

38
Mitigating Laser Rayleigh Backscatter

• Evaluate impact of unwanted Rayleigh backscatter
  on NGAO system performance
• Status
• Evaluated the intensity of the Rayleigh as well
  as aerosol and cirrus backscatter as seen at the
  Keck focal plane
• Surveyed the available lasers and pulse formats
• Surveyed methods of blocking Rayleigh
• Interim results at NGAO meeting 3 (12/13/06)
• Best rejection choice appropriately pulsed laser
  which can have a gated return so that almost no
  Rayleigh background is encountered
• However, most powerful promising lasers in
  terms of sodium return per Watt, are CW

39
LGS Asterism Geometry

• Find the simplest LGS asterism geometry meeting
  the performance budget goals
• Number of guidestars
• Constellation configuration
• Constellation size
• Conclusions
• Simulations of tomography generally validate the
  theoretical scaling laws
• 5 LGS constellation works ok on 20 arcsec field
• 7-9 LGS will be needed on 90 arcsec field
• KAON 429

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Multi-Object vs Multi-Conjugate AO

• Understand potential risks, technical challenges,
  limitations, advantages room for improvement
  with Multi-Object (MOAO) Multi-Conjugate (MCAO)
• Calculated performance for 1, 2 3 DM MCAO
  systems compared to small sub-field IFU or
  imager arms, each with a DM
• Conclusions
• MCAO offers a contiguous field for imaging, but a
  large error term. Generalized anisoplanatism
  dominates in wide-field cases
• MOAO greatly reduces anisoplanatic error at cost
  of non-contiguous field
• KAON 452

MOAO
MCAO
Hybrid
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Summary

• Management update
• Systems Engineering Management Plan in place
• Executive Committee working well together
• Ramp up slower than planned, but team processes
  now in place
• Good technical progress is being made
• Technical update
• Iterations between science requirements
  performance budgets are achieving our goals of
  understanding what is really needed
• Learning what we need to from architecture trade
  studies
• Building base for design choices cost/benefit
  trades
• We now have the management structure, plan
  enthusiastic team to produce an excellent NGAO
  System Design.