1. System Architecture WBS 3.1 Mid-Year Replan Richard Dekany NGAO Team Meeting #6 April 25-26, 2007 UCSC

2. 2 Outline Performance Budgets Trade Studies Architecture Definition Process –Process –Pivots –Object Selection Subsystem Requirements Definition

3. 3 Trade Studies After the Indian Wells point design meeting, we defined a set of open questions to address and inform the NGAO SD phase –An initial list of > 50 questions was pare to 28 studies intended to inform the architecture definition process (in concert with science requirements and performance budgets) –Goal was to capture critical issues Some of these trade studies have uncovered research areas –Scope has sometimes increase, slowing overall progress Some of these studies have changed our priorities –This was expected and indeed the original motivation for scheduling a mid-year replan

4. 4 WBS 3.1.1 Changes Red indicated cancellation Yellow indicates uncertainty Observing Efficiency and Uptime Budgets will be addressed after architecture definition

5. 5 WBS 3.1.1 Detail

6. 6 WBS 3.1.2 Changes Red indicates cancellation The plurality of these because of the realization that the topic was being addressed elsewhere in the plan. Some priorities have shifted due to new approaches since Indian Wells. A couple studies remain important, but have been reduced in priority relative to keeping to the architecture definition schedule

7. 7 WBS 3.1.2 Detail

8. 8 WBS 3.1.3 System Architecture This work package will define the baseline NGAO system architecture Inputs –System Requirements –Performance Budgets –All NGAO trade studies Outputs –Baseline Architecture –Initial Cost Estimate –System Architecture Summary Document –Initial Draft System Design Manual

9. 9 System Architecture Definition Define functional architecture elements –e.g. laser wavefront sensor Review requirements, performance budgets, and trade study conclusions –Iterate with the Science Team Propose candidate subsystems –Evaluate performance, risk, and cost –Prioritize subsystems –Conduct technical reviews Propose candidate architectures –Evaluate performance, risk, and cost –Iterate with the Science Team Adopt architecture baseline –Document rationale and issues pertinent to alternative architectures

10. 10 Summary Performance and Trade period is wrapping up Focus shifting to System Architecture Definition –May - Aug 2007 System Architecture Summary Subsystem Functional Requirements Initial NGAO Cost Estimate Initial Draft System Design Manual (milestone 8/28/07) Subsystem design work packages to begin upon subsystem prioritization