2nd convergence workshop: introduction

1
2nd convergence workshopintroduction

• R. T. Schilizzi
• Penticton
• 22 July 2004

2
SKA Development Plan

• 2000-7 technology prototyping and demonstrators
• 2004-5 site testing
• 2006 selection of site, major external review
  of design
• 2007 prepare funding proposal for 5 area
  demonstrator
• 2008 selection of technical design (may be a
  combination)
• 2009 start construction of 5 demonstrator on
  selected site
• 2010 submit funding proposal for full array
• 2012 start full construction
• 2015 initial operations
• 2020 complete construction

3
the selection process for SKA design concept

• we plan to select the technical design in 2008
  following concept prototyping and demonstration
• we recognise that the SKA is affordable only
  through a global collaboration, so we need find
  ways to keep all SKA players on-board even if
  their national concept is not selected
• Selection criteria
• captures significant fraction of the science in
  the Key Science Projects
• demonstrated engineering feasibility and
  compatibility with site choice
• maintainable at a reasonable cost
• upgradable
• within the nominal cost envelope of 1B Euro/

4
the selection process for SKA design concept

• ISSC-defined options for the selection process in
  order of desirability from an international point
  of view (anno 2003)
• mutual convergence to a single cooperative design
  concept that is inclusive and engages the global
  community
• down-selection amongst cooperative designs
  including combinations of two or more concepts
  (hybrids), and
• down-selection amongst individual concept team
  proposals

5
Selection process a year on..

• Option 1 looks unlikely in view of the timelines
  for proving the individual concepts via
  demonstrators
• We can already see that no single design concept
  can meet all the key science requirements, so.
• How viable is option 2, the hybrid idea? Are
  there combinations of designs that capture all
  the key science goals, and yet remain within the
  nominal 1B/ budget..
• Or, do we rescope the project either as a hybrid
  or as an individual concept with less than the
  full key science complement

6
What did we accomplish in the 1st convergence
workshop?(see memo 48)
We narrowed the hybrid options down to 5
possibilities

• AAT SD
• CYL SD
• LAR

• (LL SD)
• (LL CYL)
• SDfpa now added

• We discussed SKA pathfinders and noted a number
  of niche-science/national large scale
  demonstrators under consideration. Concern was
  noted w.r.t. resources for the full SKA.
• We discussed the broad issue of the continued
  engagement of the community over the long period
  between now and 2020

7
Information requested on hybrids

• frequency range of each hybrid component
• sketch of component collecting areas within
  stations and central arrays
• updated costing info
• Aeff/Tsys for each hybrid component at band edges
• Type of antenna elements and dimensions
• FOV
• for each hybrid component stations,
  antennas/station, Aphys/station, Aeff/station,
  station dimensions, shadowing limits
• Array configuration, total bandwidth transmitted,
  station or antenna FOV at spot freq
• Feeds, focal plane arrays, RF beamforming,
  bits/sample
• Sharing of station and central infrastructure

8
End of introduction
9
Issues for Discussion

• Hybrids, even with decrease of Aeff, are still
  1.5-2 B/ (including contingency and management)
  projects
• Can we afford a hybrid at all - what are the
  perils of multiple technologies from the
  construction and operation viewpoint?
• Are there any new hybrid solutions requiring
  attention?

10
Issues for Discussion

• Should we give higher priority to the science
  goals in one part of the nominal frequency range
  and select one of the design concepts in that
  frequency range?
• Or do we concentrate on short baselines first
• Or reduce the FOV spec?
• Or should we go for 2 B/?
• up-front for a full-scale hybrid or
• over a 20-year period and phase the construction
  of the SKA such that, say, the low frequency
  component (0.1 lt ? lt1.5 GHz) is built first,
  followed later by the high frequency component
  (1.2 lt ? lt 25 GHz)

• Keep cost, risk, benefit clearly in focus
• Evolutionary process?

11
Global demonstrator

• Should any large-area international demonstrator
  be a hybrid?
• Can the global astronomy community afford more
  than one large-area demonstrator?
• If AAT is to be the final technology at low freq
  (and it is still too expensive for a large area
  demonstrator in 2009), could SDfpa be an
  intermediate solution for the demonstrator?

12
Strategies for the SKA
SKA memo 45 0.1lt ? lt25 GHz, Aeff/Tsys 20000,
20mlt baselinelt3000km
6 individual concepts
3 hybrids
Cost lt1 B/?
yes
no
no
Select hybrid in 2008
Develop process to optimise scientific return
rescope
Increase nominal budget
hybrid
Construct international 5 demonstrator
hybrid
Prioritise key science select on ?, baseline,
FOV
phased Implementation of priorities 2 sites?
Select individual concept in 2008
Construct full SKA
Construct international 5 demonstrator
Select? 5 demonstrator ?construct SKA
Construct SKA
13
Issues for Discussion

• Has the existing descriptive process reached a
  useful conclusion?
• How should the design convergence process
  proceed?
• Wait for the system definition document from the
  EWG. Use cost/performance tool for hybrids as
  well
• Further develop Jaap Bregmans generic approach
• designate a reference design concept.
• Is the AATSD the front-running hybrid on the
  long term for the SKA?
• Prioritise science requirements, can we accept
  less than the full complement?