NGAO Build to Cost Summary

1
NGAO Build to Cost Summary

• Peter Wizinowich, Sean Adkins, Rich Dekany,
• Don Gavel, Claire Max the NGAO Team
• SSC Meeting
• April 14, 2009

2
Presentation Sequence

• Success Criteria, Deliverables Approach
• Science Priorities
• AO Design Changes
• Science Impact
• Revised Cost Estimate
• Assessment of Review Deliverables Conclusion
• Build-to-Cost Review Materials (user name
  password NgaoSDR)

3
Review Success Criteria

• The revised science cases requirements continue
  to provide a compelling case for building NGAO
• We have a credible technical approach to
  producing an NGAO facility within the cost cap
  and in a timely fashion
• We have reserved contingency consistent with the
  level of programmatic technical risk
• These criteria, plus the deliverables
  assumptions, were approved by the Directors
  presented at the Nov. 3, 2008 SSC meeting

Reviewers found that these criteria were
successfully met
4
Cost Reduction Approach

• Review update the science priorities
• Review other changes to the estimate (e.g.
  NFIRAOS cost comparison)
• Update the cost estimate in then-year
• Evaluate the recommended cost reductions
• As architectural changes
• As a whole including performance predictions
• Revise cost estimate
• Revisit review success criteria deliverables

5
Science Priorities
6
Key Science Drivers

• Five key science drivers were developed for the
  NGAO SDR (KAON 455)
• Galaxy assembly star formation history
• Nearby Active Galactic Nuclei
• Measurements of GR effects in the Galactic Center
• Imaging characterization of extrasolar planets
  around nearby stars
• Multiplicity of minor planets
• We discussed how our recommended cost reductions
  impact this science.

7
Science Priority Input SDR Report

• From the SDR review panel report (KAON 588)
  executive summary
• The panel supported the science cases
• The panel was satisfied with the science
  requirements flow down error budget
• The panel was concerned about complexity
  (especially the deployable IFS)
• The panel had input on the priorities
• Sky Coverage for NGAO is essential

8
Science Priority Input Keck Scientific Strategic
Plan

• From the Keck SSP 2008
• NGAO was the unanimous highest priority of the
  Planetary, Galactic, Extragalactic (in high
  angular resolution astronomy) science groups.
  NGAO will reinvent Keck and place us decisively
  in the lead in high-resolution astronomy.
  However, the timely design, fabrication
  deployment of NGAO are essential to maximize the
  scientific opportunity.
• Given the cost and complexity of the
  multi-object deployable IFU instrument for NGAO,
  , the multi-IFU instrument should be the lowest
  priority part of the NGAO plan.
• Planetary recommendations in priority order
  higher contrast near-IR imaging, extension to
  optical, large sky coverage.
• Galactic recommendations in priority order
  higher Strehl, wider field, more uniform Strehl,
  astrometric capability, wide field IFU, optical
  AO
• Extragalactic high angular resolution
  recommendations a balance between the highest
  possible angular resolution (high priority) at
  the science ? high sensitivity

9
Science Implications of no Multiplexed d-IFU

• Galaxy Assembly and Star Formation History
• Reduced observing efficiency
• Single target observed at a time
• Calibrations (e.g., sky, telluric, PSF) may
  require dedicated observing sequences
• Decreases overall statistics for understanding
  processes of galaxy formation and evolution
• Can be supplemented with complementary HST
  JWST results at higher z
• General Relativity in the Galactic Center
• Decreased efficiency in radial velocity
  measurements (fewer stars observed at once)
• Can gain back some of efficiency hit with a
  single on-axis IFU that has higher sensitivity
  (especially for galaxy assembly) larger FOV
  (especially for GC)

9
10
Flowdown of Science Priorities(resultant NGAO
Perspective)

• Based on the SDR science cases, SDR panel report
  Keck Strategic Plan
• High Strehl
• Required directly, plus to achieve high contrast
  NIR imaging, shorter ? AO, highest possible
  angular resolution, high throughput NIR IFU
  high SNR
• Required for AGN, GC, exoplanet minor planet
  key science cases
• NIR Imager with low wavefront error, high
  sensitivity, 20 FOV simple coronagraph
• Required for all key science cases.
• Large sky coverage
• Priority for all key science cases.
• NIR IFU with high angular resolution, high
  sensitivity larger format
• Required for galaxy assembly, AGN, GC minor
  planet key science cases
• Visible imaging capability to 800 nm
• Required for higher angular resolution science
• Visible IFU capability to 800 nm
• Visible imager IFU to shorter ?
• Deployable multi-IFS instrument (removed from
  plan)
• Ranked as low priority by Keck SSP 2008
  represents a significant cost

Included in B2C Excluded
11
AO Design Changes to Support Build-to-Cost
12
NGAO System Architecture

• Key AO Elements
• Configurable laser tomography
• Closed loop LGS AO for low order correction over
  a wide field
• Narrow field MOAO (open loop) for high Strehl
  science, NIR TT correction ensquared energy

X
13
Revised NGAO System Architecture

• Key Changes
• 1. No wide field science instrument ?
• Fixed narrow field tomography
• TT sharpening with single LGS AO
• 75W instead of 100W
• Narrow field relay not reflected
• 2. Cooled AO enclosure smaller
• 3. Lasers on elevation ring
• 4. Combined imager/IFU instrument
• no OSIRIS
• 5. Only one TWFS

14
AO Design Changes Summary

• Architectural changes allowed by no deployable
  multi-IFS instrument
• LGS asterism WFS architecture
• Narrow field relay location
• New design choices that dont impact the
  requirements
• Laser location
• AO optics cooling enclosure
• Design choices with modest science implications
• Reduced field of view for the wide field relay
  (120 vs 150 dia.)
• Direct pick-off of TT stars
• Truth wavefront sensor (one visible instead of 1
  vis 1 NIR)
• Reduced priority on NGS AO science
• Fixed sodium dichroic, no ADC fewer NGS WFS
  subaperture scales
• No ADC implemented for LOWFS (but design for
  mechanical fit)
• OSIRIS role replaced by new IFS
• Significant reduction in complexity
• 37 less motion control, 2 vs 8 dichroics, 9x
  smaller tomography volume

15
Performance Analysis Summary

• 31 science asterism 3 pointable lasers has
  excellent performance for narrow field science
• Overall performance comparable to estimates at
  SDR

16
Wavefront Error versus Laser Power
50W in science asterism
17
Strehl Ratio versus Laser Power
50W in science asterism
18
Performance versus Sky Coverage
EE (70 mas)
1d Tilt Error (mas)
EE (41 mas)
K-band b 30?
19
Performance versus Sky Coverage
Strehl
Z-band b 30?
20
Off-axis Performance
Imaging radius requirement
Max. IFU radius
Max. imager radius
Median seeing
21
Science Instrument Design Changes

• NGAO Proposal had three science instruments (20M
  in FY06 )
• Deployable multi IFS instrument
• NIR imager
• Visible imager
• For the SDR we included OSIRIS integration with
  NGAO
• Science instrument design changes that impact the
  science capabilities
• No deployable multi IFS instrument
• Addition of single channel NIR IFS
• Removal of OSIRIS (science capabilities covered
  by NIR IFS)
• No visible imager
• Extension of NIR imager IFS to 800 nm (possibly
  650 nm)

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NGAO Imaging Capability

• Broadband
• z, Y, J, H, K (0.818 to 2.4 µm)
• photometric filters for each band plus narrowband
  filters similar to NIRC2
• Single plate scale
• selected to optimally sample the diffraction
  limit, e.g. ?/2D or 8.5 mas at 0.818 µm
• FOV
• 34.8" x 34.8" with 8.5 mas plate scale
• Simple coronagraph
• Throughput 60 over full wavelength range
• Sky background limited performance

23
NGAO IFS Capability

• Narrowband
• z, Y, J, H, K (0.818 to 2.4 µm)
• 5 band pass per filter, number as required to
  cover each wave band
• Spectroscopy
• R 4,000
• High efficiency e.g. multiple gratings working in
  a single order
• Spatial sampling (3 scales maximum)
• 10 mas, e.g. ?/2D at 1 ?m
• 50 to 75 mas selected to match 50 ensquared
  energy of NGAO
• Intermediate scale (20 or 35 mas) to balance
  FOV/sensitivity trade off
• FOV on axis
• 4" x 4" at 50 mas sampling
• possible rectangular FOV (1" x 3") at a smaller
  spatial sampling
• Throughput 40 over full wavelength range
• Detector limited performance

24
OSIRIS role replaced by new IFS

• Carefully reviewed OSIRIS role
• In consultation with Larkin McLean
• Determined that a new IFS was required by science
  requirements
• Higher sensitivity, higher spatial resolution
  larger FOV needed
• Minor science benefit to having both new IFS
  OSIRIS
• Perhaps some plate scales
• Perhaps some multiplexing if new IFS deployable
  (extra cost)
• More overall science benefit to continuing to use
  OSIRIS on K1
• NGAO cost savings design freedom in not having
  to implement OSIRIS

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Impact on Science Requirements
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Impact on ability to meet Science Requirements
Key Science Driver SCRD Requirement Performance of B2C
Galaxy Assembly(JHK bands) EE ? 50 in 70 mas for sky cov 30 (JHK) EE gt 70 in 70 mas for sky cov ? 90 (K band)
Nearby AGNs(Z band for Ca triplet) EE ? 50 in 1/2 grav sphere of influence EE ? 25 in 33 mas ? MBH ? 107 Msun _at_ Virgo cluster (17.6 Mpc )
General Relativity at the Galactic Center(K band) 100 ?as astrometric accuracy ? 5 from GC Need to quantify. Already very close to meeting this requirement with KII AO.
Extrasolar planets around old field brown dwarfs (H band) Contrast ratio ?H gt 10 at 0.2 from H14 star (2 MJ at 4 AU, d 20 pc) Meets requirements (determined by static errors)
Multiplicity of minor planets (Z or J bands) Contrast ratio ?J gt 5.5 at 0.5 from J lt 16 asteroid Meets requirements WFE 170 nm is sufficient
v
v
v
v
v
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B2C Design Changes only modest effect on meeting
science requirements
v

• Galaxy Assembly B2C exceeds SDR requirements
• Nearby AGNs B2C doesnt meet EE requirement
  (didnt meet at SDR either). Still in
  interesting regime for BH mass measurements (MBH
  ? 107 Msun _at_ Virgo cluster). Need to review
  more clearly define requirement.
• General Relativity at the Galactic Center Key
  variables (e.g. differential tilt jitter,
  geometric distortion in AO instrument,
  differential atmospheric refraction) not strongly
  affected by laser power. Confusion only slightly
  worse than SDR design.
• Extrasolar planets around old field brown dwarfs
  contrast ratio not affected by B2C design
  changes. Static errors dominate.
• Multiplicity of minor planets Meets SDR
  requirements

v
v
v
v
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NGAO comparison to JWST TMT

• Higher spatial resolution for imaging
  spectroscopy than JWST
• JWST much more sensitive at K. NGAO more
  sensitive at J between OH lines at H
• Lots of NGAO science possible in 5 years prior to
  TMT 1st science
• Key community resource in support of TMT science
  (do at Keck 1st if can)
• Could push to shorter ? or multi-object IFS or
  as TMT arrives on scene
• NGAO could perform long term studies (e.g.,
  synoptic, GC astrometry)

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NGAO comparison to JWST

• Evaluation of key science cases

30
NGAO comparison to TMT

• NGAO NFIRAOS wavefront errors are the same
  (162 vs 174 nm rms)
• Similar Strehls but higher spatial resolution for
  TMT
• Similar spatial resolution for IFU science but
  higher sensitivity for TMT

31
Revised Cost Estimate
32
Revised Cost Estimate

• Including all proposed cost reductions new cost
  estimates

33
Revised Cost Estimate

• Cost estimation methodology approved at SDR
• NFIRAOS comparison improved confidence in
  estimate
• Revised estimate incorporates new information
• IFS design (ATI) K2 center launch (MRI)
  proposal estimates
• Better laser cost estimates (ESO, GMT, TMT, AURA
  collaboration)
• NGAO contingency has increased from 22.6 to
  24.2
• Due to increased laser contingency (30 based on
  NFIRAOS comparison)
• Contingency has not been decreased for the
  reduced complexity
• Conservative in reducing labor hours for
  build-to-cost
• NGAO instruments at proposal level
• Estimate well anchored to other instrument costs
  (NIRC2, OSIRIS, MOSFIRE, IRIS)
• 30 contingency assumed post-design

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Assessment of Build-to-Cost Review Deliverables
Success Criteria Conclusions
35
Review Deliverables Summary (1 of 2)

• Revisions to the science cases requirements,
  the scientific impact
• Galaxy assembly science case requirements need
  to be modified for a single IFU instead of
  multiple deployable IFUs
• Only minor impacts on all other science cases
• Major design changes
• Design changes documented in KAON 642
• Performance impact of design changes documented
  in KAON 644
• Major cost changes
• All cost changes documented with comments
  equations in cost book summary spreadsheet by WBS
  and phase
• Viewed as better tool than cost book for tracking
  changes

36
Review Deliverables Summary (2 of 2)

• Major schedule changes
• No major schedule changes assumed
• 2 month slip in milestones assumed for cost
  estimate
• New plan needs to be developed as part of
  preliminary design
• Preliminary design phase replan is a high
  priority post this review
• Contingency changes
• Reviewed contingency as part of NFIRAOS cost
  comparison
• Laser, potentially RTC, increase identified as
  needed
• Laser contingency increased to 30
• Other bottom-up contingency estimates viewed as
  sufficient especially given reduction in
  complexity with design changes

37
Conclusions

• The build-to-cost guidance resulted in a simpler
  therefore less expensive NGAO facility with
  similar science performance
• Primarily achieved at the expense of a
  significant science capability (e.g., the
  multiple deployable IFS)
• We will address the recommendations from the B2C
  review during the preliminary design
• And report on how we addressed these
  recommendations at the PDR
• Our management priorities are switching to
• Replanning completing the preliminary design in
  a timely fashion
• Developing a viable funding management plan for
  delivering NGAO in a timely fashion as a
  preliminary design deliverable

38
Starting Cost Estimate

• Start from SDR cost estimate
• additional contingency (per NFIRAOS cost
  comparison)
• updated NIR visible imager cost estimates (no
  instrument designs yet)
• - deployable multi-IFU (14M FY06 estimate 17M
  in then-year )
• fixed NIR IFU (very rough estimate) 3.5
  inflation/year