Alan R. Whitney MIT Haystack Observatory e-VLBI – Creating a Global Radio-Telescope Array via High-Speed Networks Alan R. Whitney MIT Haystack Observatory Optical Waves: Who Needs Them and Why? Internet2 Fall Member Meeting Chicago, IL 5 Dec 2006

Traditional VLBI The Very-Long Baseline Interferometry (VLBI) Technique (with traditional data recording) The Global VLBI Array (up to ~20 stations can be used simultaneously)

VLBI Science VLBI astronomy example ASTRONOMY Highest resolution technique available to astronomers – tens of microarcseconds Allows detailed studies of the most distant objects Plate-tectonic motions from VLBI measurements GEODESY Highest precision (few mm) technique available for global tectonic measurements Highest spatial and time resolution of Earth’s motion in space for the study of Earth’s interior Earth-rotation measurements important for military/civilian navigation Fundamental calibration for GPS constellation within Celestial Ref Frame VLBI astronomy example

e-VLBI Data Rates and Volume Typical astronomy experiment at 1 Gbps/station ~10 TB/station/day Global 20-station experiment  ~200 TB/day Single 10-day experiment can produce up to 2 PB Higher data rates yield higher signal-to-noise ratio in final results Data rates of 8 to 64 Gbps are already on the horizon and can only be sustained by e-VLBI  too much data to economically record and ship

e-VLBI Characteristics Experiments scheduled well in advance; duration typically several hours to several days Data rate is constant over long periods of time; typically 128Mbps to several Gbps, extending to many Gbps in future Data are uncompressible white Gaussian noise For real-time processing, latency must be typically <~1 sec Some data loss (up to a few percent) can usually be tolerated Intermediate network storage may be useful in some situations These characteristics are well suited to using optical waves

International e-VLBI Demonstrations in collaboration with DRAGON project iGRID-05 Networking Conf. San Diego, CA Sep 05 SC-05 Supercomputer Conf. Seattle, WA Nov 05 Internet2 Driving Exemplary Applications (IDEA) Award to “Very High Speed VLBI (e-VLBI)”. Alan Whitney (MIT/Haystack), Arpad Szomoru (JIVE), Y. Koyama (NICT), and Hisao Uose (NTT) Apr 26, 2006 – Arlington, VA

Challenges of e-VLBI over optical waves Easy and reliable scheduling Easy setup and teardown of optical circuits Quick identification and resolution of problems; all telescopes must be connected all the time for real-time processing Physical connection of remote telescopes to high-speed networks with optical-wave capability; proceeding well in Europe, Asia and Europe – U.S. lags Bottom line: e-VLBI and optical waves are clearly a good match and are already being successfully exploited on a limited basis for better science.