The International Laser Ranging Service (ILRS) is improving its services through network expansion and continuous upgrades of its modeling and analysis approaches. New ground stations are being deployed with higher repetition rate systems, more efficient detection, and increased automation; new technologies are also being adopted at some of its legacy stations. In addition, the roster of tracking missions is rapidly expanding. The top priority for the Service continues to be its contribution to the reference frame development, but of increasing importance is also the tracking of GNSS satellites, including the anticipated deployment of the new GPS III constellation over this decade. These requirements are being reflected in new system designs and updates. Stations are also being adapted to accommodate ground and space-time synchronization. A few stations continue with their lunar laser ranging activities while several others have begun testing their ability to do lunar ranging in the future. About a dozen stations are active in space-debris tracking for studies of orbital dynamics and reentry predictions. New tools and procedures have been implemented to improve the quality of SLR data and derived products, and to expedite the resolution of engineering issues. Work also continues on the design and building of improved retroreflector targets to maximize data quality and quantity. This paper will give an overview of activities underway within the Service, paths forward and presently envisioned, and current issues and challenges.

(1) Harvard-Smithsonian Center for Astrophysics, Cambridge, United States (mpearlman@cfa.harvard.edu), (2) NVI, Inc./NASA Goddard Space Flight Center, Greenbelt MD, United States (dirk.behrend-1@nasa.gov), (3) Jet Propulsion Laboratory/California Institute of Technology, Pasadena, CA, United States (Allison.B.Craddock@jpl.nasa.gov), (4) NASA Goddard Space Flight Center, Greenbelt MD, United States (carey.e.noll@nasa.gov), (5) University of Maryland, Baltimore MD, United States (epavlis@umbc.edu), (6) Institut Géographique National, St. Mande, France (jerome.saunier@ign.fr), (7) PSMSL, National Oceanography Centre, Liverpool, United Kingdom (antt@noc.ac.uk), (8) Politecnico di Milano, Milan, Italy (riccardo.barzaghi@polimi.it), (9) Bundesamt für Kartographie und Geodäsie, Frankfurt, Germany (Daniela.Thaller@bkg.bund.de), (10) GeoForschungsZentrum, Potsdam, Germany (benjamin.maennel@gfz-potsdam.de), (11) Rise Research Institutes of Sweden, Borås, Sweden (sten.bergstrand@ri.se), (12) Institut für Erdmessung, Hannover, Germany (mueller@mbox.ife.uni-hannover.de)

The GGOS Bureau of Networks and Observations works with the IAG Services (IVS, ILRS, IGS, IDS, IGFS, and PSMSL) to advocate for the expansion and upgrade of space geodesy networks for the maintenance and improvement of the reference frame and other applications, as well as for the integration with other techniques, including absolute gravity and sea level measurements from tide gauges. New sites are being established following the GGOS concept of “core” and co-location sites, and new technologies are being implemented to enhance performance in data yield as well as accuracy. The Bureau continues to meet with organizations to discuss possibilities, including partnerships, for new and expanded participation. The GGOS Network continues to grow as new stations join every year. The Bureau holds meetings frequently, providing the opportunity for representatives from the services to meet and share progress and plans, and to discuss issues of common interest. It also monitors the status and projects the evolution of the network based on information from the current and expected future participants. Of particular interest at the moment is the integration of gravity and tide gauge networks and the forthcoming establishment of the new absolute gravity reference frame. The IAG Committees and Joint Working Groups play an essential role in the Bureau activity. The Standing Committee on Performance Simulations and Architectural Trade-offs (PLATO) uses simulation and analysis techniques to project future network capability and to examine trade-off options. The Committee on Data and Information is working on a strategy for a GGOS metadata system for data products and a more comprehensive long-term plan for an all-inclusive system. The Committee on Satellite Missions is working to enhance communication with the space missions, to advocate for missions that support GGOS goals and to enhance ground systems support. The IERS Working Group on Site Survey and Co-location (also participating in the Bureau) is working to enhance standardization in procedures, outreach and to encourage new survey groups to participate and improve procedures to determine systems’ reference points, a crucial aid in the detection of technique-specific systematic errors. We will give a brief update on the status and projection of the network infrastructure of the next several years, and the progress and plans of the Committees/Working Group in their critical role in enhancing data product quality and accessibility to the users.

The International Laser Ranging Service (ILRS) was established by the International Association of Geodesy (IAG) in 1998 to support programs in geodesy, geophysics, fundamental constants and lunar research, and to provide the International Earth Rotation Service with data products that are essential to the maintenance and improvement in the International Terrestrial Reference Frame (ITRF), the basis for metric measurements of changes in the Earth and Earth–Moon system. Other scientific products derived from laser ranging include precise geocentric positions and motions of ground stations, satellite orbits, components of Earth’s gravity field and their temporal variations, Earth Orientation Parameters, precise lunar ephemerides and information about the internal structure of the Moon. Laser ranging systems are already measuring the one-way distance to remote optical receivers in space and are performing very accurate time transfer between remote sites in the Earth and in Space. The ILRS works closely with the IAG’s Global Geodetic Observing System. The ILRS develops (1) the standards and specifications necessary for product consistency, and (2) the priorities and tracking strategies required to maximize network efficiency. The service collects, merges, analyzes, archives and distributes satellite and lunar laser ranging data to satisfy a variety of scientific, engineering, and operational needs and encourages the application of new technologies to enhance the quality, quantity, and cost effectiveness of its data products. The ILRS works with (1) new satellite missions in the design and building of retroreflector targets to maximize data quality and quantity, and (2) science programs to optimize scientific data yield. Since its inception, the ILRS has grown to include forty laser ranging stations distributed around the world. The ILRS stations track more than ninety satellites from low Earth orbit (LEO) to the geosynchronous orbit altitude as well as retroreflector arrays on the surface of the Moon. Applications have been expanded to include time transfer, asynchronous ranging for targets at extended ranges, free space quantum telecommunications, and the tracking of space debris. Laser ranging technology is moving to lower energy, higher repetition rates (kHz), single-photon-sensitive detectors, shorter pulse widths, shorter normal point intervals for faster data acquisition, and increased pass interleaving, automated to autonomous operation with remote access, and embedded software for real-time updates and decision making. An example of pass interleaving is presented for the Yarragadee station (see Fig. 4); tracking of LEO satellites is often accommodated during break in LEO and GNSS passes. New satellites arrays provide more compact targets and work continues on the development of lighter less expensive arrays for satellites and the moon. The service now provides operational ITRF products including daily/weekly station positions and daily resolution Earth orientation products; the flow of weekly combination of satellite orbit files for LAGEOS/Etalon-1 and -2 has recently been established. New products are under testing through a pilot project on systematic error monitoring currently underway. The article will give an overview of activities underway within the service, paths forward presently envisioned, and current issues and challenges.

The International Laser Ranging Service (ILRS) through its permanent components (Tracking Stations, Operations Centers, Data Centers, Analysis Centers, Central Bureau, and Governing Board) distributes satellite and lunar laser ranging data and derived products to support global, multidisciplinary scientific research. The ILRS Data Centers and Central Bureau serve as the primary source for information, data, and products for this global user community. The ILRS website, https://ilrs.gsfc.nasa.gov , is a key tool for communication for the service, providing background information on the ILRS, its organization and operation, and detailed descriptions of ILRS components, data, and products. Links are provided to extensive information on the supported satellite missions and ILRS network stations including performance assessments and data quality evaluations. Furthermore, the website connects users to archives of laser ranging data and derived products available through the data centers. In this paper, we discuss the development of the ILRS infrastructure, its current status, website resources, description of laser ranging data and products, and plans for future enhancements.

Role of the Bureau: To advocate and encourage implementation of the Core and Co-location Network to satisfy GGOS requirements, to monitor the status of the network and project its future condition, and to support and advocate for infrastructure critical for the development of data products essential to GGOS.

Global navigation satellite system (GNSS) phase measurements of the total electron content (TEC) and ionospheric delay are sensitive to sudden increases in electron density in the layers of the Earth’s ionosphere. These sudden ionospheric disruptions, or SIDs, are due to enhanced X-ray and extreme ultraviolet radiation from a solar flare that drastically increases the electron density in localized regions. SIDs are solar flare signatures in the Earth’s ionosphere and can be observed with very low frequency (VLF ~ 3-30 kHz) monitors and dual-frequency GNSS (L1 = 1575.42 MHz, L2 = 1227.60 MHz) receivers that probe lower (D-region) to upper (F-region) ionospheric layers, respectively.

Over the past five years, the International GNSS Service (IGS) has made continuous efforts to extend its service from GPS and GLONASS to the variety of newly established global and regional navigation satellite systems. This report summarizes the achievements and progress made in this period by the IGS Multi-GNSS Experiment (MGEX). The status and tracking capabilities of the IGS monitoring station network are presented and the multi-GNSS products derived from this resource are discussed. The achieved performance is assessed and related to the current level of space segment and user equipment characterization. While the performance of orbit and clock products for BeiDou, Galileo, and QZSS still lags behind the legacy GPS and GLONASS products, continued progress has been made since launch of the MGEX project and already enables use of the new constellations for precise point positioning, atmospheric research and other applications. Directions for further research are identified to fully integrate the new constellations into routine GNSS processing. Furthermore, the active support of GNSS providers is encouraged to assist the scientific community in the generation of fully competitive products for the new constellations.

The Global Geodetic Observing System (GGOS) has been organized under the International Association of Geodesy (IAG) since 1999 to work with the IAG components to provide the geodetic infrastructure necessary for monitoring the Earth system and global change for both scientific research and to help give us the opportunity to make intelligent decisions for societal benefit. Observations include those of the Earth's shape, gravity field and rotational motion, and those such as precision satellite orbits to support space based systems (such as altimetry and gravity sensors). GGOS contributes to the emerging Global Earth Observing System of Systems (GEOSS) not only with the accurate reference frame required for many components of GEOSS but also with observations related to the global hydrological cycle, the dynamics of atmosphere and oceans, and natural hazards and disasters.

The Crustal Dynamics Data Information System (CDDIS) supports data archiving and distribution activities for the space geodesy and geodynamics community. The main objectives of the system are to store space geodesy and geodynamics related data and products in a central archive, to maintain information about the archival of these data,to disseminate these data and information in a timely manner to a global scientific research community, and provide user based tools for the exploration and use of the archive. The CDDIS data system and its archive is a key component in several of the geometric services within the International Association of Geodesy (IAG) and its observing systemthe Global Geodetic Observing System (GGOS), including the IGS, the International DORIS Service (IDS), the International Laser Ranging Service (ILRS), the International VLBI Service for Geodesy and Astrometry (IVS), and the International Earth Rotation and Reference Systems Service (IERS). The CDDIS provides on-line access to over 17 Tbytes of dataand derived products in support of the IAG services and GGOS. The systems archive continues to grow and improve as new activities are supported and enhancements are implemented. Recently, the CDDIS has established a real-time streaming capability for GNSS data and products. Furthermore, enhancements to metadata describing the contents ofthe archive have been developed to facilitate data discovery. This poster will provide a review of the improvements in the system infrastructure that CDDIS has made over the past year for the geodetic community and describe future plans for the system.

The recently reorganized GGOS Bureau of Networks and Observations has many elements that are associated with building and sustaining the infrastructure that supports the Global Geodetic Observing System (GGOS) through the development and maintenance of the International Terrestrial and Celestial Reference Frames, improved gravity field models and their incorporation into the reference frame, the production of precision orbits for missions of interest to GGOS, and many other applications. The affiliated Service Networks (IVS, ILRS, IGS, IDS, and now the IGFS and the PSMSL) continue to grow geographically and to improve core and co-location site performance with newer technologies. Efforts are underway to expand GGOS participation and outreach. Several groups are undertaking initiatives and seeking partnerships to update existing sites and expand the networks in geographic areas void of coverage. New satellites are being launched by the Space Agencies in disciplines relevant to GGOS. Working groups now constitute an integral part of the Bureau, providing key service to GGOS. Their activities include: projecting future network capability and examining trade-off options for station deployment and technology upgrades, developing metadata collection and online availability strategies; improving coordination and information exchange with the missions for better ground-based network response and space-segment adequacy for the realization of GGOS goals; and standardizing site-tie measurement, archiving, and analysis procedures. This poster will present the progress in the Bureau's activities and its efforts to expand the networks and make them more effective in supporting GGOS.