DVA1 Project Status Gary Hovey and Gordon Lacy SKA Visit, Sept NRC-Herzberg Astronomy Technology Program - Penticton

Rough Agenda 09:00 Tour DVA1 (muster in DRAO foyer) 10:00 Tour Labs (AFAD, LNA, ADC, EVLA, Kermode) 10:45 Coffee 11:00 DVA1 update (Gordon and Gary) 11:45 SKA Structure update (Dean and Gordon) 12:30 Lunch OK Falls 13:30 Tour DVA1 fabrication facility OK Falls 15:00 Coffee & wrap-up discussions at DRAO 16:00 Free 17:00 Depart DRAO 19:00 Dinner at Hooded Merganser DVA1 - Performance and Status2 of 34

Outline DVA1 Overview: Motivation, goals and objectives Key innovations Optics results Mechanical and fabrication results Testing and future plans DVA1 - Performance and Status3 of 34

SKA Dish Design Considerations ( Imaging dynamic range – The signal range in terms of intensity over which the SKA will be able to observe. It also means that the dishes have to have extremely stable pointing and accuracy in harsh desert environments. Design for mass manufacture – Making the most efficient and technically outstanding design choices, whilst keeping to a budget that comes within that set out by the SKA Organisation Low operating Cost per dish – Once built, how to maintain them and operate the telescopes on the most cost effective budget. The reliability of the dishes will be a critical factor here. Maximum sensitivity per dish - Ensuring each dish delivers the maximum sensitivity and that this is consistent between all of the dishes in the array DVA1 - Performance and Status4 of 34

DVA-1: Design Approach and Goals SKA Challenge: A leap in sensitivity and dynamic range requires a corresponding leap in antenna cost/performance. Goals and Objectives: Investigate, develop and demonstrate innovations that improve antenna cost/performance. Lower cost through −Simplicity of design −Minimal part count −Modular design −Low labour content −Minimal use of custom sizes and part −Use of advanced materials −Use of scalable mass fabrication processes −Optimal optics over the prime frequency range 1-10GHz. −Feed-up design DVA1 - Performance and Status5 of 34

DVA1: Design Approach and Goals (cont.) Improved optics and stability performance through Use of advanced materials Shaped optics to maximise A eff / T sys Improved stability over all load conditions −Feed-high design lowering peak cross section to wind −Compact turning-head and mount to minimise moments −Single piece rim supported reflector immunity to translational loads distortions uniform and low order −High stiffness and low CTE using carbon fibre composites −Composite reflector with embedded metal mesh Reflectivity of Aluminium with the stiffness of carbon. Low moving mass -> superior closed loop response Design for low maintenance upkeep and burden, as well as long life and durability DVA1 - Performance and Status6 of 34

Existing Designs Australian SKA Pathfinder Allen Telescope Array South African MeerKat DVA1 - Performance and Status7 of 34

Evolution of Improved Cost/Performance Improving Materials, Design, and Manufacturing Cost/performance DVA1 - Performance and Status8 of 34

Background Began investigating composites in 2005 Built two reflectors in 2007 Started collaboration with US-TDP in 2009 −Design phase lead by US-TDP −Construction phase lead by NRC CoDR in early 2011 PDR in late 2011 CDR in mid 2012 Fabrication reflector and pedestal mid-2013 Final assembly and test through to fall 2014 DVA1 - Performance and Status9 of 34

DVA-1: Designed for High Dynamic Range Capability High Thermal Performance Rim supported monocoque design along with very low CTE materials keeps all thermal movement both small and very uniform to minimize effect on beam pattern High Performance in Wind and Gravity Central compliant connector allows some structural sag without inducing unwanted distortion at center of dish Rim supported design keeps dish deflections to absolute minimum and concentrates any deflections at rim where effect on performance is small. Extremely deep truss back structure keeps dish shape as close to rigid as is possible. High Overall Optics Stability Secondary and feed platform support optimized to maximize stiffness using shape optimization software. Secondary and feed support tubes use zero and matched CTE carbon tubes for extremely high thermal stability. DVA1 - Performance and Status10 of 34

DVA1: Design Features The main design elements are: 15m Gregorian offset feed-high optics Unblocked aperture Large space for feeds Stiffer, lower cost than feed-low Molded single piece rim- supported composite reflectors Tubular backup structure Tubular composite feedlegs Pedestal-type mount allows small offset to elevation axis Deep truss backup structure with central pocket for pedestal mount Central compliant connector allows movement in wind without distortion DVA1 - Performance and Status11 of 34

DVA1: Estimated Sensitivity DVA-1 Aeff/Tsys using Corrugated Horns Assumes 15K Receiver DVA1 - Performance and Status12 of 34

DVA1: Estimated Performance in Wind Beam Pattern at 10 GHz. 25 kph Wind at 15 degree Elevation (Blue) Undistorted (Red) DVA1 - Performance and Status13 of 34

DVA1 Predicted Temperature Stability Beam Pattern at 10 GHz. 25 Celsius Thermal Change (Blue) Undistorted (Red) DVA1 - Performance and Status14 of 34

Beam Pattern at 18GHz 15  Elevation Undistorted (Red). 15 degree Elevation (Blue) Effect mainly a pointing correction as 25kph wind has a negligible effect on pattern DVA1 - Performance and Status15 of 34

DVA1 Primary Reflector Damage and Repairs Collapsed SurfaceAfter being popped out with air bags

DVA1 Repair Activities

DVA-1 Reflector Repairs

DVA-1 Reflector Accuracy After Repairs Post repair error = 1.0mm rms Excluding repaired areas error = 0.7mm rms Notes: 1.Errors are from ideal and include mold errors. 2.No aperture weighting used, otherwise rms error would be less.

DVA-1 Secondary Reflector Accuracy Un-weighted by illumination: Surface error = 0.2mm rms Weighted by illumination Surface error = 0.11mm rms

Improved Results: GDSatcom Secondary Reflector We have now built two sub reflectors for the GDSatcom Meerkat project RMS of reflector 0.090mm Mold RMS 0.058mm

DVA-1: Composite Performance Structural TestComposite Design Consideration Metallic Design Consideration Creephigh static load Static StrengthMaterial properties Fatigue LifeHigh cyclic load Glass Transition Temp.Choose resin with sufficiently high value. NA Impact ResistanceEngineering requirement Galvanic CorrosionEncapsulate reflective layerPaint and primer UV, Moisture, Humidity Paint (no primer required) and resin properties Paint and Primer Reflectivity DegradationPaint (no primer required)Paint and Primer Fungus growthPaint DVA1 - Performance and Status22 of 34

Surface Resistance Measurements TE 011 Mode Resonant Frequency8.4 GHz14.6 GHz18.4 GHz Test SampleSurface resistance (Ohms/square) Aluminium 6061-T Copper DVA1 Reflector Test Panel Improved Layup Test Panel TE 011 Mode Resonant Frequency8.4 GHz14.6 GHz18.4 GHz Test SampleEquivalent Noise Temperature in K Aluminium 6061-T Copper Secondary Reflector Test Panel Improved Layup Test Panel DVA1 - Performance and Status23 of 34

Pointing: Preliminary Tilt Measurements DVA1 - Performance and Status24 of 34

Coefficient of Thermal Expansion (CTE) Tests CTE values are notoriously difficult to measure in composite materials Lab CTE values were compared with field measurements taken on the primary reflector Results compare very well Data Source CTE value ( μm/m o C) Toray Coupon Testing5.62 (no error values given) DRAO test August 6 th ± Aluminum (for comparison)23.6 DVA1 - Performance and Status25 of 34

Primary Dish Deflection as a Function of Elevation Angle Primary reflector positional data tracked with a laser tracker for 19 points over elevation angles ranging from 20 degrees up to 85 degrees. Experiment was conducted at night to minimize temperature variations Data has not yet been interpolated to the full dish surface Initial results in tabular form look consistent with CAD model predictions. Deviations within a few millimeters. DVA1 - Performance and Status26 of 34

Primary Dish Deflection Target Layout DVA1 - Performance and Status27 of 34

Primary Dish Deflection Tabular Data, Delta Z values Point # Delta Z errors in mm for 19 tracked points as a function of elevation angle. DVA1 - Performance and Status28 of 34

Primary Dish Surface Scan, Rim Horizontal (Bird Bath). Primary reflector surface deviations. RMS error, uncorrected for aperture weighting 0.89mm Most of surface is within ±1.0mm (green) Most red areas are repaired areas, a result of the helicopter incident Almost all other features are in the mold surface (horizontal banding, grid feature in upper right quadrant). DVA1 - Performance and Status29 of 34

First Light Spectra to GHz Nimiq 6 Ku band Satellite 12.2 to 12.7 GHz DVA1 - Performance and Status30 of 34

First Beam Scan Results (Preliminary) DVA1 - Performance and Status31 of 34

RF Testing Ku band holography Aperture/surface errors Antenna pattern Pointing behaviour Stability Repeatability Performance over load cases, gravity, wind and temperature Sensitivity Tipping curves Aperture efficiency Ku Band Horn MeerKat L-band receiver DVA1 - Performance and Status32 of 34

Cost ItemMaterialsLabourSub-contractTotals Reflectors, feed platform and support structures Composite Dish Surface, Secondary, Central Reinforcement$111,000$63,400 Composite Backing Pieces, fabrication portion, not including molds$23,250 Dish Rim Connector, labour (material in line 3)$14,000 Ball studs$6,132 PDSS$84,874 Feed Platform$6,700 Secondary Support Structure $85,000 Sub Totals$111,000$77,400$205,956$394,356 Pedestal Components Tower, contract with Minex Engineering$300,000 Tower, misc extra parts, package 1$19,920 Tower, misc extra parts, package 2$90,600 Tower, additional items$14,836 Drive system (motors, control system and encoders)$43,000 Painting$5,000 Sub Totals $473,356 Grand Total$867,712 DVA1 - Performance and Status33 of 34

Issues and Technical Risks Key retired technical (technology) risks Composite reflectors meet requirements for −Reflectivity −Mechanical and thermal properties −Surface accuracy Outstanding risks now very low. −Majority have been mitigated by simulation/measurement −Those remaining will be retired by RF testing DVA1 - Performance and Status34 of 34

35 Questions? Gary Hovey, Project Manager Gordon Lacy, Project Engineer DVA1 - Performance and Status35 of 34