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Build to Cost Meeting:
Major NGAO system cost savings ideas
Don Gavel
NGAO Team Meeting
September 11-12, 2008
Performance Space
• Shrink performance along axes to cut costs
• Not necessary to cut all axes uniformly
• Know the consequence of each reduction
Wavelength
• Science Impact
• Marginal Cost Reduction
Strehl
• Decide what is a “core” defining NGAO that
fits the cost cap and is still worth the cost
Sky
Coverage
Field of View
(Regard)
Contrast
Sensitivity /
Throughput /
Emissivity
Multiplicity of
Instruments
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Major Cost Savings Scopes
• Cut Laser Power – by a third?, by one half?
– Eliminate wide field d-IFS, concentrate science in 30 arcsec field
– 6 LGS, 3 roving for point and shoot, 3 are fixed
• Remove one of the two AO relays
– Fewer optomechanical components
– Improved throughput
– Not split-relay
• Pare down or eliminate the “switchyard”
– Reduced number of instruments
– One focal plane (shared for science & LOWFS)
– Reduced number of dichroics and changers
• Reduce automation
– Sacrifice “instant” configurability
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More Cost Savings Scopes
• Cut number of instruments
– Refurbish and reuse OSIRIS
– Combined visible/IR sensor in imager
– Pare down dIFS multiplicity – one dIFS? Two dIFS with shared dewar?
• Purchase science imagers from commercial supplier
– Live with specs from off-the-shelf design
• Make the opto-mechanics physically small
– Off-the shelf optics and mounts
– Smaller space to enclose and cool
• Cut number of actuators
– Trade with other error budget elements to minimize impact
– Limiter: short wavelength coverage
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Even More Cost Saving Scopes
• Accelerate the project plan
– “Then-year” dollars loose value over time (with inflation)
– Not necessary to finish earlier, just spend earlier – maybe by
overlapping portions of design and FSD phases
• Reduce technical risk
– Targeted prototyping and simulations
– Avoid overruns due to rework of uncertainty/untested systems failing to
meet expected performance on first implementation
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