The Project Office Perspective Antonin Bouchez 1GMT AO Workshop, Canberra Nov. 2010

2 Outline 1.Project Status 2.AO requirements 3.Baseline Design 4.Unresolved technical issues 5.Meeting goals GMT AO Workshop, Canberra Nov. 2010

Project Status We’re working towards project PDR in “early” AO PDR must precede this; planning for Dec New project manager Keith Raybould starts Dec. 6. Major replanning effort has begun -Restructured WBS -Bottoms-up cost estimate (to complete by January 2011) Previous cost estimate for AO: $58.6 M (2004 $) -Schedule through construction (complete ~March 2011?) Current direction from management: Design to the the science requirements, without cost constraint. GMT AO Workshop, Canberra Nov

Thoughts on AO project management AO system will likely cost ~$75M. Most of this work will have to be done by industry. However, AO/instrument groups at partner institutions provide experience, design expertise, and an ideal environment for technology development and testing. We’re very aware that project organization, systems engineering, and communications must be improved. Launching online communications tools (Basecamp) Hiring additional systems engineers Instituting a change control board GMT AO Workshop, Canberra Nov

55 ModeDescription Natural Guide Star AO (NGSAO) High Strehl over a narrow field of view using bright guide stars. Requirement: 160 nm RMS WFE for R<8 stars. Laser Tomography AO (LTAO) Moderate Strehl over narrow field of view with high sky coverage Requirement: 200 nm RMS WFE over 80% of sky at b=50°. Ground Layer AO (GLAO) Image improvement over very wide field of view by correcting only low-altitude turbulence. Goal: 2-4x image size reduction in near-IR over 8’ diameter. Top-level performance requirements GMT AO Workshop, Canberra Nov Additional Requirements: Shall not preclude future implementation of MCAO and MOAO observing modes. AO system shall have <20% emissivity (<10% goal).

Instrument-specific Requirements 4 instruments currently being studied, with a wide range of AO requirements not captured in top-level requirements: GMTIFSNGS/LTAO with strict tip/tilt requirements GMTNIRSNGS/LTAO with loose tip/tilt requirements TIGERHigh Strehl – potentially NGS only NIRMOSGLAO only Challenge for AO team is to design a single system which will suit any 1-2 of these which are selected for 1 st light construction. Our strategy: -Design common components (ASM, lasers, RTC) which meet the most stringent requirement. -Design a suite of sensors which can meet requirements of each mode, and assume that the selected instruments will only implement certain sensors. -Do this with minimum duplication of effort: eg. only 1 IR-WFS design. GMT AO Workshop, Canberra Nov

AO System Baseline Design 7 On-axis LGS Projector Free space beam relay Lasers: 6x30W CW + spare 7x672 actuator adaptive secondary mirror Wavefront sensors: Visible WFS modules attach to front of instruments: 1 HO-WFS, 3 LO-WFS, 6 LGS-WFS 1 IR-WFS internal to instrument which require high sky coverage 1 Optical Phasing Sensor common to all instruments top view Separate GLAO dichroic & LGS-WFS assembly GMT AO Workshop, Canberra Nov. 2010

8 Phasing System Baseline Design GLAO: No phasing necessary NGSAO: Use a pyramid NGS sensor to sense both telescope & atmospheric piston. LTAO: Slow (~1 min) Optical Piston Sensor with large patrol area + fast (100 Hz) relative metrology of adjacent segments. Average over atmospheric piston and accept 120 nm RMS WFE. Various alternative LTAO piston sensing approaches have been discussed, but none demonstrated to be sufficiently general. GMT AO Workshop, Canberra Nov. 2010

AO System Design Effort 5 components to the preliminary design effort: UANGSAO and GLAO subsystems ANULTAO subsystems SAOOptical phasing sensor ADS/MGAdaptive secondary mirror Proj. OfficeSystems engineering, edge sensors Potential additional design contracts to industry: Real- time computer, … GMT AO Workshop, Canberra Nov

Unresolved Technical Questions Sky coverage & NGS sensor architecture… Can we develop an IR WFS design which suits all instrument’s needs? Are any of the alternative LTAO optical piston sensor approaches worth pursuing? Need to define and simulate interaction between AO and piston control loops. Are active optics WFS necessary/useful in NGSAO or LTAO control loop? Could active optics WFS be sufficient for all NGS sensing in GLAO mode? GMT AO Workshop, Canberra Nov

Unresolved Management Questions What systems & sensors are crucial to prototype? -Optical Phasing Sensor… sensitivity & seeing dependence GMT AO Workshop, Canberra Nov

[My] Meeting Goals We agree on a baseline design, including which aspects are yet to be defined. We agree on various groups’ responsibilities for the preliminary design phase, and the critical interfaces between these subsystems. We set up a schedule for communication between groups on design & interfaces. We compile a list of the technical questions which need to be resolved, and assign these to individuals. We compile a list of management and systems engineering issues which the project office must address. GMT AO Workshop, Canberra Nov

End 13GMT AO Workshop, Canberra Nov. 2010