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Square Kilometre Array: Project Overview

Square Kilometre Array: Project Overview. Richard Schilizzi International SKA Project Office CERN 21 January 2005. Outline. the SKA in 2 slides why build it? concept, site choice technical issues SKA governance, funding, and timeline. Square Kilometre Array.

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Square Kilometre Array: Project Overview

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  1. Square Kilometre Array: Project Overview Richard Schilizzi International SKA Project Office CERN 21 January 2005

  2. Outline • the SKA in 2 slides • why build it? • concept, site choice • technical issues • SKA governance, funding, and timeline

  3. Square Kilometre Array extremely powerful survey telescope at radio wavelengths-capability to follow up individual objects with high angular and time resolution ~ 1 km2 collecting area; sensitivity ~100 x currently most powerful telescope (VLA) -survey speed is 10000 x faster than VLA wide frequency range: 0.1 – 25 GHz (goal) wide field of view: ≥1 sq. degree at 1.4 GHz (5 x area of moon) -goal: many tens of sq. deg.

  4. Square Kilometre Array goal of multi-beam instrument at lower frequencies construction cost 1 B€; operating cost 50 M€ per year “born global”; 45 institutes in 17 countries actively involved

  5. The history of the universe

  6. Actually, we dont know much

  7. Key Science Projects • probing the dark ages before the universe lit up • the evolution of galaxies and large scale structure in the universe (equation of state of dark energy) • strong field tests of gravity using pulsars and black holes • the origin and evolution of cosmic magnetism • the cradle of life; movies of planetary formation; ETI • + • exploration of the unknown • SKA science case (eds: C. Carilli, S Rawlings) published by Elsevier in New Astronomy Reviews, vol 48, pp989-1163, December 2004 (see also www.skatelescope.org)

  8. Galaxies in optical light and atomic hydrogen M81 in optical light M81 in atomic hydrogen

  9. Equation of state of dark energy via atomic hydrogen surveys with SKA • dark energy alters distance measures in cosmology • power spectrum of the clustering of galaxies likely to contain a signature of acoustic oscillations seen in the CMB at time of recombination • use scale of acoustic oscillations as a cosmological standard ruler to measure equation of state of dark energy at intermediate redshift and possibly its evolution. 0.5<z<1.5 optimal • evolution of the HI content of the universe. CMB SKA HI surveys from C. Blake, S. Rawlings et al

  10. Pulsars tell us about gravity • …almost Black Holes • …objects of extreme matter • …relativistic plasma physics in action • …probes of turbulent and magnetized ISM • …precision tools, e.g. - Period of B1937+21: • P = 0.0015578064924327  0.0000000000000004 s • Orbital eccentricity of J1012+5307: e<0.0000008 • …testing ground for theories of gravity – pulsar-black hole binary • …cosmological gravitational wave detectors

  11. Watch planets forming Hubble Space Telescope: optical scattered light Very Large Array: 7mm dust emission (radio) Simulation of a gap in a protoplanetary disk caused by a forming planet High sensitivity + high angular resolution required

  12. SKA SKA ATA ATA Phoenix Phoenix Intelligent life elsewhere? SKA as Search Engine

  13. SKA Concept up to at least 3000 km from inner array ~100 Software: control&monitoringcorrelation calibration image formation archiving scheduling 2000 antennas

  14. Example SKA configuration 20% of total collecting area within 1 km diameter 50% of total collecting area within 5 km diameter 75% of total collecting area within 150 km from coremaximum baselines at least 3000 km from array core

  15. SKA in Argentina

  16. KARST (Landsat) SKA in China

  17. SKA in North America Core @ VLA

  18. Antenna concepts • Large diameter reflecting flux concentrators • Small diameter dishes • Aperture phased arrays Large adaptive reflectors Spherical telescopes Cylinders Small dishes. I Small dishes.II Aperture array tiles Small dishes+aperture arrays in the focus Major technical challenge for the SKA: reduce cost/m2 by a factor of 10 compared with current telescopes

  19. Antenna innovations Low-cost dense arrays for aperture and focal planes Active surfaces for large reflectors Broadband feeds Suspended or airborne inertial feed platform Cheap, accurate 12m dishes using hydroforming or preloading

  20. Data transport • High data rates • 1-2 Tb/s from stations desirable • 80 Gb/s from individual antennas in central array • “Commercially realistic” ~ 100 Gb/s for longer links • 100 Gb/s on trans-continental and trans-oceanic links allows ~ 1 “full” SKA image per minute (1TB) to be transported from imaging engine • Digital fibre links throughout array • Information transport costs may dominate processing costs • Local oscillator/timing is a challenge for a highly-distributed array

  21. SKA Correlators • Cross-correlation (multiply-accumulate) is the basis of interferometry • 1 MAC per sample • Number of correlations ~ N2 / 2 ~ 3 x 106 • Inp. data rate ~ 3 PB/s • MAC rate ~ 3 P op/s • Output data rate ~ 30 M correlations / s

  22. DSP or HPC? • Line between DSP and general purpose computers will be blurred Courtesy Eugene de Geus

  23. Post-correlation calibrationimagingarchivedistribution Hardware • Wide-field imaging is probably the cost driver • RFI mitigation could also be expensive • Calculate wide-field imaging costs in 2004 (from simulations) and scale with Moore’s Law Assume that ML holds for computing costs, not necessarily for per CPU costs • AND that we achieve large scale parallelization at good efficiency • Bottom line: perhaps aim for 100Pflops in 2015 for €100M • If 100Pflops is beyond the state of the art in 2015, we’ll have to scale back our scientific ambitions until it is.

  24. Software • Estimating total software effort required is hard at this stage of the project • Projecting from ALMA (Atacama Large Millimeter Array) 1000 – 2000 fte • Projecting from LOFAR (Low Frequency Array)  250-500 fte

  25. Technology Project Management Wideband, efficient antennas Sensitive, low-cost receivers Fast, long-distance, data transport High performance DSP & computing hardware New data processing and visualization techniques Evolving science goals High levels of technical risk International politics Ambitious delivery timescale Industry liaison Pre-competitive alliances + procurement + project delivery SKA challenges Performance + Cost

  26. Who’s doing what around the world? • Europe SKA Design Study (SKADS); Pharos; LOFAR; eEVN; eMERLIN • USA NSF Technology Development Program; Allen Telescope Array; EVLA; potential site • Canada Canadian Large Adaptive Reflector • Australia small dishes+FPAs; potential site • India small dishes • China Five-hundred-metre Aperture Spherical Telescope FAST); potential site • Sth Africa small dishes+FPAs; potential site • Argentinapotential site

  27. International Science Advisory Committee International Engineering Advisory Committee International SKA Steering Committee Executive Committee International Site Selection Advisory Committee International Collaboration Working Group International SKA Project Office Engineering Working Group Site Evaluation Working Group Science Working Group Simulations Working Group Outreach Committee Operations Working Group 8 task forces 2 task forces 6 task forces 1 task force SKA management structure

  28. SKA development funds • 38 M€ committed to SKA development so far around the world • Current proposals for funds • Aperture Array Tiles – SKA Design Study (EU FP6 + matching: €38M, 2004-8) • Small Dishes – SKA Technology Development Program (NSF: $US 31M, 2005-9) • Small Dishes+AA – Australia (CSIRO: $AU 15M, 2005-8) -- South Africa (Government: R70M, 2005-8) • Large Adaptive Reflector - LAR Technical Development (NRC: $CA 12M, 2005-9) • Development via SKA “pathfinders”comes for freetelescopes that are precursors to the SKA and will prove major technology components for the SKA, eg LOFAR, EVLA, Allen Telescope Array, eMERLIN, eEVN,…

  29. International timeline • 1995-2008 technology prototyping • 2005 site testing • 2006 site decision (September) • 2007 major external review of technical designs • 2009 select technical design (may be a combination) • 2009 submit proposals for phased development of SKA • 2010 start construction of Phase 1 on selected site • 2013 implementation readiness review for full array • 2014 start construction of full array • 2020 complete construction

  30. SKA information www.skatelescope.org SKA newsletter 2x per year

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