Geodetic Networks: The Supporting Framework

1. Geodetic Networks: The Supporting Framework • Terrestrial Reference Frame is ‘Critical Infrastructure’ for all Earth science research and applications. • Global geodetic networks are a fundamental component of all ESE roadmaps. • Geodetic network is one of SESWG’s seven observation strategies to address the fundamental solid Earth questions. • Maintenance of the global geodetic network, the Terrestrial Reference Frame, and Earth Orientation Parameters is the “supporting framework”: an element of the fully realized solid Earth program.

2. Geodetic Networks: Production of ITRF • Networks include SLR, VLBI, GPS ground system • Data and products are provided to the research community via international services: IGS, ILRS, IVS. • Techniques are complementary in unique capabilities • SLR provides geocenter • VLBI provides UT1 • GPS provides densification • Techniques are interdependent • Sensitive to different systematic errors • Use of UT1 by satellite techniques • Use of satellite origin by VLBI • Current consistency and accuracy of ITRF • 1-3 cm positions, mm/yr velocities • Xxx pole position • 3 µs UT1 • Sub-nanosecond timing distribution (?)

3. Geodetic Networks: 5-year outcome • Reference frame realized by coordinated multi-technique networks and analysis • consistency and accuracy sub-centimeter globally • Vertical component improvement • Access to the improved ITRF in real-time for all users, the consistent, robust and accurate global grid • Improvement in network and sub-network distributions and characteristics and efficiencies • Real-time GPS global subnetwork • eVLBI • SLR2000 • Analysis development and validation to optimize multi-technique combinations • Improved data and product access interfaces • Implement SEEDS philosophies at data and information systems (CDDIS - GSFC/CBIS - JPL)

4. Geodetic Networks: NASA’s role • Networks are critical infrastructure and strategic US assets • NASA leverages extensive resources by cooperating with international partners • International partnerships, cooperation and coordination are unique to NASA and must continue - as only NASA can • Geodetic services coordinating offices are largely funded by NASA (IGS at JPL, ILRS&IVS at GSFC) • International coordination is critical to this success (idea of a standardized approach with global partners) • Benefits? - access to a much larger, enhanced data set, product redundancy

5. Geodetic Networks: Issues and Challenges • Integrating new technology into networks • Maintaining and upgrading aging equipment and hardware • Developing new analysis techniques as new equipment becomes available • Identifying a mechanism by which the support for these vital resources can be shared by all users within NASA

6. Transition to GPS slides

7. Geodetic Network: GPS Strengths

8. Geodetic Networks: GPS Stations Map

9. Geodetic Networks: GPS Technology Development

10. Geodetic Networks: IGS Structure

11. Geodetic Networks: GPS Analysis

12. Geodetic Networks: GPS Issues and Challenges

13. Geodetic Networks: GPS 5-year Plan

14. Transition to SLR slides

15. Geodetic Networks: SLR Unique Capabilities

16. Geodetic Networks: SLR Site Map

17. Geodetic Networks: SLR Current Challenges

18. Geodetic Networks: SLR Next Generation System

19. Geodetic Networks: SLR Products

20. Geodetic Networks: ILRS Structure

21. Geodetic Networks: VLBI

22. Geodetic Networks: VLBI Station Map

23. Geodetic Networks: IVS Structure IVS has 73 Permanent Components, representing 37 institutions in 17 countries. NASA supports the IVS Coordinating Center, Network Coordinator, and 7 Permanent Components

24. Geodetic Networks: VLBI Unique Capabilities • CRF • Celestial pole • UT1-UTC • Differential navigation for spacecraft

25. Geodetic Networks: VLBI Issues and Challenges • Improve temporal coverage from 3.5 days/week to full time. • Decrease time delay from 15 days to near-real time. • Improve global configuration with more stations in the southern hemisphere. • Address serious RFI problem at S/X (2.2/8.4 GHz) by moving to higher RF bandwidths, e.g. K/Q (22/28 GHz). • Replace aging antennas. • Upgrade aging data acquisition equipment. • Establish fiber networks for electronic data transfer to remove the need to ship media from stations to correlator.

26. Geodetic Networks: VLBI Technology Advances Mark 5 disk-based recording system • Media cost only $1.25/GB (half of tape) • Allows higher bandwidth recording • Enables automated/unattended operation • Allows electronic data transfer and near real time processing e-VLBI for data transfer • Gb/s data transfer demonstrated • Global experiment program for international transfer near Gb rates • New adaptive IP protocol studies

27. Geodetic Networks: VLBI 5-year Plan • 2004 • Deploy and use Mark 5 at all correlators and stations • Establish e-VLBI for daily UT1 measurements • Study K/Q for using a higher dual frequency RF band • 2005 • Begin replacement of Fairbanks antenna • Begin development of K/Q receivers • 2006 • Establish e-VLBI network of NASA stations with international partner stations • Begin replacement of data acquisition hardware with digital interfaces • 2007 • Fairbanks antenna complete • 2008 • e-VLBI networks in use for 3-4 days/week EOP and TRF measurements • Initial K/Q test installations

28. Geodetic Networks: NASA’s Geodetic Networks • Transition to integration slides – delete text box then insert map as picture from file

29. Geodetic Networks: Integration Elements • Proposed activities • NGO proposal: National Geodetic Observatory • Focus US efforts in space geodesy to integrate techniques, attract new funding • INDIGO proposal: Inter-Service Data Integration for Geodetic Operations • Goal: to enable improved performance, accuracy, and efficiency in support of NASA’s Earth science and international user community by developing and providing uniform access to heterogeneous space geodetic data systems. • International organizations • IERS: International Earth rotation and Reference systems Service. • Compiles and distributes ITRF, ICRF, EOP time series • Pilot project on rigorous combination of data from all techniques • IAG: International Association of Geodesy • IGGOS: Integrated Global Geodetic Observing System, flagship project • IGGOS is expected to play a major role in geodesy community, integration of techniques at a very high level

30. Geodetic Networks: Co-location Strategy • Importance of co-location • Co-location ties techniques together, enables combinations • Local ties • accurate measurements of vectors between reference points for different techniques at a site. • essential for combination of data from different techniques. • limiting factor in closure of the networks • Approach or strategy • Improve local tie measurements. • Understand different solution results for each technique at a site. • Improve the co-location network. • Investigate new technology approaches to measuring local ties.

31. Geodetic Networks: Next Steps Toward Integration • Global networks are NASA ‘critical infrastructure’ and strategic US assets. • Meeting challenges together for mutual strength • Continue and extend cross-technique coordination. • The goal of integration is the most stable and accurate reference frame and tracking capabilities. • The three techniques plan to jointly assess the structure and budget for the NASA networks and recommend an approach for integration. • An integrated program should achieve • appropriate balance of measurements, scientific needs and resources in the mix of VLBI, GPS and SLR. • appropriate balance of resources for scientific research and applications with the demanding requirements of the TRF and the geodetic networks infrastructure.