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.

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 (?)

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)

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

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

•Transition to GPS slides

Geodetic Network: GPS Strengths

Geodetic Networks: GPS Stations Map

Geodetic Networks: GPS Technology Development

Geodetic Networks: IGS Structure

Geodetic Networks: GPS Analysis

Geodetic Networks: GPS Issues and Challenges

Geodetic Networks: GPS 5-year Plan

•Transition to SLR slides

Geodetic Networks: SLR Unique Capabilities

Geodetic Networks: SLR Site Map

Geodetic Networks: SLR Current Challenges

Geodetic Networks: SLR Next Generation System

Geodetic Networks: SLR Products

Geodetic Networks: ILRS Structure

Geodetic Networks: VLBI

Geodetic Networks: VLBI Station Map

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

Geodetic Networks: VLBI Unique Capabilities

• CRF

• Celestial pole

• UT1-UTC

• Differential navigation for spacecraft

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.

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

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

Geodetic Networks: NASA’s Geodetic Networks

•Transition to integration slides – delete text box

then insert map as picture from file

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

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.

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.