Copyright 2007 Northrop Grumman Corporation 1 Large Deployed and Assembled Space Telescopes November 14, 2007 Ronald S Polidan Chief Architect, Civil Systems Division Charles F Lillie, Gary Segal, Dean Dailey Northrop Grumman Space Technology

Copyright 2007 Northrop Grumman Corporation 2 Agenda  Expectations  Deployable Observatories  Very Large Observatories  Technology Needs

Copyright 2007 Northrop Grumman Corporation 3 Astrophysics Beyond 2020 – Expectations  JWST will have launched in 2013, fulfilled its 5 year prime mission and be on its way to its 10-year lifetime goal  New “infrastructure” elements and technologies are changing the architectural approaches to big space telescopes  Bigger launch vehicles: EELV Heavy and Ares V  Advanced optics technology (ultra-light weight mirrors, replication, improved wavefront sensing and control technologies, …)  Advanced deployment and assembly (robotic or crewed) technologies  Linearly extrapolating from the past:  Hubble (1990): 2.4 m aperture, 11,110 kg total mass, $4.1 B (FY06, A-D)  JWST (2013): 6.5 m aperture, 6,200 kg total mass, $3.5 B (FY06, A-D)  For a similar cost we should expect to produce a ~20 m telescope, launching in the mid-2020s  Assuming anything faster than linear technology development produces 25 meter or larger filled aperture telescopes 20-m or Larger Filled Aperture Telescopes Should be Expected in the 2020’s

Copyright 2007 Northrop Grumman Corporation 4 Current State of the Art: JWST Momentum Trim Flap Fixed Fwd and Aft Spreader Bars Aft UPS Bipod Launch Lock Attachment Points Unitized Pallet Structures (UPS) Telescopic Side Booms Fixed Side Spreader Bars Note: S/C Solar Array and Radiator Shades Shown in Stowed Positions for Clarity Momentum Trim Flap Fixed Width Aft Membrane Core Area Tower Ext. SMSS Deployment PM Deployment Secondary Deployment SunshieldSolar ArraysHGA Cool Down

Copyright 2007 Northrop Grumman Corporation 5 Simplest Approach: Scaling Up JWST  Scaling up JWST to large EELV and Ares V launch vehicles  Lowest cost option: a JWST “rebuild” with no new technology development  Use identical cord fold deployment & sunshield architecture and technology  The bottom line for several reasons but mostly having to do with vertical height in the faring (a high center of gravity, load paths and acoustic loads are additional complications) limits you to  ~ 8 meter aperture for the largest EELV  ~ 12 meter aperture for an Ares V  For truly large telescopes, we need something more advanced than a cord fold approach

Copyright 2007 Northrop Grumman Corporation 6 Shift to a Family of Deployment Options Recent analysis driven by the proliferation of diverse missions requiring both large and smaller telescopes have shown that the choice of deployment approach will depend on: Manufacturing, Launch & Deployment Risk and Cost Monolith Primary Mirror Diameter (m) Relative Risk & Cost vs Primary Diameter Hubble Spitzer Stacked Hex Fan- Fold Chord-Fold JWST Size of the primary mirror required for the mission Launch constraints –Total mass –Launch environment Required telescope agility –Fixed targets or –Imaging while tracking Applicable and available mirror technology –Need smaller, stiffer segments –Availability of larger, ultra-light segments Acceptable cost and risk

Copyright 2007 Northrop Grumman Corporation 7 Telescope Deployment Architecture Approach Should be Optimized for Cost and Mission Needs 2m - 18 Segment PM, 2m Fairing2m - 7 Segment PM, 2m Fairing3m - 7 Segment PM, 3m Fairing 3m - 10 Segment PM, 2m Fairing4m - 10 Segment PM, 2m Fairing3m - 7 Segment PM, 2m fairing Depending on manufacturability of segments Depending on segment size & Mission Rqmts Scalable to Very Large Diameters Chord-Fold Deployment Fan-Fold DeploymentRobotic Deployment

Copyright 2007 Northrop Grumman Corporation 8 Scaling to Very Large Apertures One of our long term goals has been the development of an efficient deployment approach that would scale to very large telescopes SAFIR (10m) 2m Segments 6m Primary 3m Segments 8.5m Primary 3.5m Segments 10.5m Primary 1m Segments 3m SMD Primary Scaling in Segment Size 2m Segments 10m Primary 3.5m Segments 24.5m Primary Scaling in Number of RingsHybrid Mirror 6m UV/Vis/IRSMD (3m) ● ● ●  Minimal additional structure required for launch  Tripod secondary support contributes to PM stiffness  Heritage concept with hardware implementation experience  Scalability to very larger telescopes  Most efficient packaging  No outboard mechanisms allowing minimal shroud diameter Advantages of Stacked Hex Deployment 28m UV/Vis/IR

Copyright 2007 Northrop Grumman Corporation 9 Stowed in EELV 5 m heavy (Restraint shell removed for clarity) 10 meter, 7 hex segment deployment scheme JWST bus subsystem re-use New telescope payload Far infrared wavelength detection requires ~ 4 deg K cooling Positioning boom Deploys and positions scope Thermally decouples scope from sunshield Very low frequency, highly damped jitter isolation Maintains balance between mass and pressure centers over large F.O.R. Lower frequency telescope attachments provide greater observatory flexibility and performance! SAFIR Observatory Concept

Copyright 2007 Northrop Grumman Corporation 10 Application of NGST High Accuracy Reflector Deployment System (1990) Stack Deployment Animation

Copyright 2007 Northrop Grumman Corporation 11 Thermal And Dynamic Isolation Boom Thermal and dynamic isolation boom concept with fine pointing Produces ~3 Pi steradian instantaneous field of regard Allows for improved momentum management by control of CP/CG

Copyright 2007 Northrop Grumman Corporation 12 “Sugar Scoop” Conical Advanced Sunshield Approaches Flat The level of thermal stability being demanded by future big telescope missions preclude the use of simple sunshields Need to look toward multi-layer or possibly active sunshields These too will need to be deployed

Copyright 2007 Northrop Grumman Corporation 13 Scaling to Very Large Apertures  Long standing analysis and design confirms that deployment of stacked, Hex segments provides the most efficient approach to scaling to large telescope apertures Scale the number of deployed rings Scale the size of the segments  Two basic approaches to scaling segmented telescopes: Issues Deployment of large number of segments Largest number of rigid body actuators Highest weight ratio Highest number of segment prescriptions Issues Highest risk of manufacturability of very large segments Requires largest faring diameter

Copyright 2007 Northrop Grumman Corporation 14 Structurally Connected Interferometer – 40 m

Copyright 2007 Northrop Grumman Corporation m spherical primary mirror telescope 30 meter spherical primary mirror Secondary (f/d = 1.79) Spherical corrector assembly

Copyright 2007 Northrop Grumman Corporation m Assembled Spherical Telescope concept Bus and telescope rendezvous and dock here

Copyright 2007 Northrop Grumman Corporation M Spherical Telescope Observatory Concept  Five EELV heavy launches  Total lift capability ~ 40,000 Kg’s  Observatory SWAG ~ 27,000 Kg’s  Weight margin ~ 48%

Copyright 2007 Northrop Grumman Corporation 18 Courtesy of Jack Frassanito & Associates and Dr. Harley Thronson On-orbit Servicing

Copyright 2007 Northrop Grumman Corporation 19 Key Technologies Enabling Next Generation Space Telescopes  Rapid, low cost fabrication of ultra-light weight primary mirror segments  Eliminates time consuming grinding and polishing  Several approaches including vapor deposition of nanolaminates bonded to actuated substrates  Active figure control of primary mirror segments  High precision actuators  Surface parallel actuation eliminates need for stiff reaction structure (SMD)  High speed wavefront sensing and control  High density figure control enables very light weight mirror segments  High speed, active while imaging WFS&C allows for rapid slew and settle and earth imaging  Highly-packageable & scalable deployment techniques  Deployment architecture should take advantage of light weight mirrors  Active control for light weight structural elements to supply good stability  Reduces weight required for vibration and thermal control Image Plane & WFS&C Sensor Imaging FPA (4096 X  m pixels) Model Sensor Scene Tracker Focal Plane Fine Figure & Phase Sensor Beam Footprint at FPA Plane Nonolaminate on Mandrel

Copyright 2007 Northrop Grumman Corporation 20 Conclusions  Space telescopes with 20-meter and larger apertures are within affordable reach by the mid-2020’s  To achieve this we need to initiate a technology development plan that thoroughly explores the trade options and identifies and matures the enabling technology  We need the sustained technology development funding to mature the technology

Copyright 2007 Northrop Grumman Corporation 21