Project News


  • A speed bump in space-time Earthdata Article Featuring CDDIS PublishedRelease Date: 12/04/2014 Like many physicists today, Rafael Lang at Purdue University is on the hunt. As in a treasure hunt, the odds of finding the treasure may be slim, but the rewards are huge and the lure of the hunt irresistible. Lang said, "If we were to find something, it would be super, super exciting, another puzzle piece to open this new world."

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  • 19th ILRS workshop logo 19th International Workshop on Laser Ranging a great successRelease Date: 11/18/2014 The 19th International Laser Ranging Workshop was hosted by NASA GSFC from October 27-31, 2014 in Annapolis, Maryland. October 31 marks the 50th anniversary of the first successful Satellite Laser Ranging (SLR) measurement which occurred at the Goddard Geophysical and Astronomical Observatory (GGAO) in 1964. The theme for this workshop, "Celebrating 50 Years of SLR: Remembering the Past and Planning for the Future" allowed the community to look back on its many accomplishments and to present plans for future advances in SLR technology and science. Sponsors for the Workshop were NASA, the Smithsonian Astrophysical Observatory (SAO), and the International Laser Ranging Service (ILRS). The Workshop was organized by Carey Noll (NASA GSFC, CDDIS DAAC Manager), Jan McGarry (NASA GSFC), Mike Pearlman (SAO) and Stephen Merkowitz (NASA GSFC) and was attended by approximately 180 participants from 25 countries.

    On Monday, the history of SLR was given in a series of six invited talks by the pioneers in the field. The afternoon was devoted to invited science talks showing SLR's positive impact on various NASA and international missions.

    In addition to the events in Annapolis, the participants were given a day-long tour of GSFC and GGAO, including tours of the Goddard Visitor's Center, Building 7 Integration and Testing facilities, Building 29 James Webb Space Telescope (JWST) integration and testing, and tours of the NASA next generation space geodesy systems at GGAO. A Goddard Joint Engineering and Scientific Colloquium on Wednesday featured a seminar by John Degnan, "A Celebration of Fifty Years of Satellite Laser Ranging." John's talk was introduced with a few words from GSFC Center Director, Chris Scolese.

    A new format for a station operations session was introduced at this workshop where ILRS experts met in small groups of station engineers and operators to provide solutions to common station problems, information to maintain station stability, and guidelines for interacting with the analysts in determining station biases. These station clinics were well attended and received by workshop attendees.

    A highlight of the Workshop was a speech and question and answer session at Thursday evening's banquet given by Dr. Piers Sellers, GSFC Deputy Director of the Sciences and Exploration Directorate and NASA astronaut.

    There were 81 oral presentations and 70+ posters at the Workshop. The Goddard participants were authors or co-authors of over 30 of these, with many highlighting the new Space Geodesy Satellite Laser Ranging (SGSLR) Systems and the Next Generation Space Geodesy Network. SGSLR and the Space Geodesy Network will be built by Space Geodesy Project at Goddard for global deployment over the coming decade.

    This workshop in Annapolis and GSFC proved to be a very successful gathering of international experts in the field of satellite laser ranging. The workshop website (http://cddis.gsfc.nasa.gov/lw19) will soon be updated with presentations, posters, summaries, and photos from the week.
  • 19th ILRS workshop logo 19th International Workshop on Laser Ranging - Celebrating 50 years of SLRRelease Date: 09/24/2014 The National Aeronautics and Space Administration (NASA), along with the Smithsonian Astrophysical Observatory, and the International Laser Ranging Service (ILRS), are pleased to announce that the 19th International Workshop on Laser Ranging will be held in Annapolis Maryland during the week of October 27-31, 2014 at the Historic Inns of Annapolis.

    October 31, 2014 will mark the 50th anniversary of the first successful SLR measurement, conducted at what is now the Goddard Geophysical and Astronomical Observatory (GGAO). The theme for this workshop, "Celebrating 50 Years of SLR: Remembering the Past and Planning for the Future" will allow us to look back on our many accomplishments and present plans for future advances in SLR technology and science.

    Visit the workshopp web site
  • NGSLR Celebrating 50 Years of Satellite Laser Ranging at NASA Goddard Space Flight CenterRelease Date: 08/28/2014 We like to think of Earth as a big blue marble; a shimmering, smooth sphere. In reality, our home planet is shaped more like a big blue potato (or, to be polite and more scientific, an “oblate spheroid”). The combination of Earth’s rotation at roughly 1,670 kilometers per hour, the uneven distribution of continents that are slowly moving, the Moon’s tug on tides, ocean circulation, and a host of other factors cause our planet to have an uneven surface that is a bit flat at the poles and slightly bulging around the middle.

    This means that the Earth’s exact shape, center of gravity, and precise rotation are constantly changing and can only be determined through extremely precise measurements. An entire field of science called geodesy is devoted to taking these precise measurements, and Goddard Space Flight Center is at the leading edge of this field. In fact, it was in a field near Goddard 50 years ago this October that the first successful Satellite Laser Range (SLR) measurements were taken, ushering in a new era in the science of measuring the Earth.

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  • GGIM Logo Ruth Neilan (NASA JPL) appointed to the rank of official U.S. Delegate Advisor for the United Nations to UN Global Geospatial Information Management (GGIM)Slide showRelease Date: 08/26/2014 During the week of August 4-8, Ruth Neilan (NASA JPL) participated in and attended the following meetings at the United Nations in New York, Department of Economic and Social Affairs, UN Statistics Division:
    • Fourth Session of the United Nations Committee of Experts on Global Geospatial Information Management (UN-GGIM)
    • United Nations Global Forum on the Integration of Statistical and Geospatial Information
    • Global Geodetic Reference Frame (GGRF) Working Group Meeting
    • UN-GGIM regional splinter sessions

    Because of her involvement in these critical areas, Ruth has been appointed to the rank of official U.S. Delegate Advisor for the United Nations to UN GGIM.

    On August 4-5, a meeting was held on "The Integration of Statistical and Geospatial Information" with significant focus on the Global Geodetic Reference Frame (GGRF). Wednesday, August 6, began with a workshop on the GGRF. The GGRF Working Group is chaired by Australia and Norway (Gary Johnston, Anne Jørgensen and Per Erik Opseth); included in the core working group (WG) are Zuheir Altamimi, Hansjörg Kutterrer, and Ruth Neilan, as key members of the GGRF working group; with larger WG including many country representatives.

    The GGRF Working Group tabled a Terms of Reference, a draft UN General Assembly Resolution for the GGRF, and a Concept Note at the 4th Session of the UN Community of Experts on GGIM. After a presentation given by Gary Johnston on August 6, there were 40 extremely positive interventions in support of the work of GGRF – the sheer number of countries formally declaring support for this effort is remarkable and demonstrates that the GGIM's work has had significant impact in the diplomatic sphere.

    The draft resolution and its intent were approved by the 77 representative countries. This resulted in an official decision, 4/101, recommending that the amended draft Resolution on a Global Geodetic Reference Frame for Sustainable Development, be referred to the Economic and Social Council for endorsement and further referral to the United Nations General Assembly. The decision also noted the commitment of Member States to provide support in this process.

    This resolution, and the tremendous diplomatic and technical effort behind it, highlights the importance of the global geodetic reference frame, its maintenance, upgrade, and collocation of techniques. Additional time was spent in the WG on August 8, laying out the 'GGRF Roadmap' and other supporting strategies. Related documents and information about the GGRF meeting can be found on the web at: http://ggim.un.org/ggim_committee.html

    GEO Secretariat, Barb Ryan, was also present at the GGRF workshop and voiced her support of the GGRF on behalf of GEO. In complement to this, Ryan has written a strong support letter for GGRF and will work jointly with the team within the GEO/CEOS committees and the UN GGIM. This will also be a topic at the UN International Committee on GNSS within UN OOSA, which hosted a UN GGIM preparatory meeting this past April in Vienna, Austria.

    For the official UN press release detailing the sessions of the UN Committee of Experts on GGIM and links to corresponding documents, please visit: http://www.un.org/News/Press/docs//2014/stat452.doc.htm.

    More information on the GGIM Global Forum, August 4-5 can be found at: http://ggim.un.org/Global%20Forum.html.

    Space Geodesy Community Representatives:
    • Gary Johnston, Geoscience Australia; Chair of GIAC, Member of the IGS Governing Board
    • Per Erik Opseth and Anne Jørgensen, Norwegian Mapping Authority (Kartverket), NASA partners, Ny Alesünd Station
    • Zuheir Altamimi, Institut National de l'Information Géographique et Forestière (IGN); ITRF and Member of the IGS Governing Board
    • Hansjörg Kutterrer, Bundesamt für Kartographie und Geodäsie (BKG); Chair of GGOS
    • Ruth Neilan, NASA JPL; Vice Chair of GGOS, Director of the IGS Central Bureau
  • 18th Laser Ranging Workshop logo Proceedings from the 18th International Workshop on Laser Ranging Release Date: 03/25/2014 A website for the proceedings from the 18th International Workshop on Laser Ranging, held November 11-15, 2013 in Fujiyoshida Japan, has been created and is now available at http://cddis.gsfc.nasa.gov/lw18/.

    Because a hardcopy of the proceedings will not be published, all presentations, posters, and papers collected thus far have been made available through this website. Session summaries and ILRS splinter meeting notes are also linked on the website. The ILRS would like to acknowledge the significant, and thorough, efforts of the program committee in working with workshop participants to collect the documents that are now available through the website.
  • CDDIS Logo New CDDIS website now availableRelease Date: 03/24/2014 The CDDIS staff is pleased to announce a new CDDIS website is now available. This redesign has allowed for a review of the organization of the site and its contents, ensuring information is current and useful. The new site also incorporates an improved navigation scheme. The website features access to applications enabling data discovery. One application, the SiteLogViewer, provides an enhanced display and comparison of the contents of ILRS and IDS site logs used by the services to document a site's system configuration; IGS and IVS site logs will be added to the utility in the near future.

    Comments and suggestions are welcome and should be directed to the CDDIS support group through the "Contact Us" link. We would like to acknowledge the efforts of the website development team (Lori Tyahla, Nathan Pollack, and Carey Noll) for their contributions to the site content.
  • Goddard Logo Robert H. Goddard Award RecipientsRelease Date: 03/18/2014 Congratulations to the Space Geodesy Project Team for receiving the Robert H. Goddard Exceptional Achievement Group Award for Engineering (group photos GSFC | MIT). Additional congratulations goes to Jan McGarry, who received an individual Robert H. Goddard Award for Exceptional Engineering Achievement.
  • NASA logo Network outage - Saturday, March 15, 2014 from 08:00 a.m. through 04:00 p.m. EDT (12:00-20:00 UTC) Release Date: 03/07/2014 We have been notified that there will be a network outage (due to work on NASA's backbone equipment) on Saturday, March 15, 2014 from 08:00 a.m. through 04:00 p.m. EDT (12:00-20:00 UTC). Unfortunately, this activity will affect CDDIS operations. All connectivity to our servers will be off-line during that time. The outage will also affect access to the CDDIS, ILRS, LRO-LR, and Space Geodesy Project websites.

    While the CDDIS is unavailable, users can access one of the other data centers supporting the services:

    We regret the inconvenience the outage will cause our user community.
  • Space Geodesy Project logo NASA Solar System Exploration Division Seminar Release Date: 01/29/2014 An SSED seminar will be held Monday, February 10 from 2 to 3 p.m. in Building 34, Room W150. The speaker, Dr. Zuheir Altamimi from IGN in France, will give a presentation entitled "The International Terrestrial Reference Frame: current status and future challenges."
  • ILRS logo 19th International Workshop on Laser Ranging AnnouncedRelease Date: 01/21/2014 We are pleased to announce that the 19th International Workshop on Laser Ranging will be hosted at NASA Goddard Space Flight Center, October 27-31 2014. Goddard has the unique opportunity to host this event at the birthplace of SLR: October 31, 2014 will mark the 50th anniversary of the first SLR measurement, conducted at what is now the Goddard Geophysical and Astronomical Observatory, GGAO. The theme for this workshop, "Celebrating 50 Years of SLR: Remembering the Past and Planning for the Future" will allow us to look back on our many accomplishments and present plans for future advances in the SLR technique. Furthermore, we solicit contributions from complementary space geodesy techniques and from activities that rely on the integration of SLR with other space geodesy techniques.

    Please consider participation in this workshop and reserve the week to join us at NASA GSFC. More details will be provided shortly.
  • NASA logoNASA Earth and Space Science Fellowship (NESSF) Program Release Date: 12/23/2013 NASA announces a call for graduate fellowship proposals to the NASA Earth and Space Science Fellowship (NESSF) program for the 2014-2015 academic year. This call for fellowship proposals solicits applications from accredited U.S. universities on behalf of individuals pursuing Master of Science (M.Sc.) or Doctoral (Ph.D.) degrees in Earth and space sciences, or related disciplines. The purpose of NESSF is to ensure continued training of a highly qualified workforce in disciplines needed to achieve NASA’s scientific goals. Awards resulting from the competitive selection will be made in the form of training grants to the respective universities.

    The deadline for NEW applications is February 3, 2014, and the deadline for RENEWAL applications is March 17, 2014.

    The NESSF call for proposals and submission instructions are located at the NESSF 14 solicitation index page at http://nspires.nasaprs.com/ - click on "Solicitations" then click on "Open Solicitations" then select the "NESSF 14" announcement. Also refer to “Proposal Submission Instructions” and “Frequently Asked Questions” listed under “Other Documents” on the NESSF 14 solicitation index page.

    All proposals must be submitted in electronic format only through the NASA NSPIRES system. The advisor has an active role in the submission of the fellowship proposal. To use the NSPIRES system, the advisor, the student, and the university must all register. Extended instructions on how to submit an electronic proposal package are posted on the NESSF 14 solicitation index page listed above. You can register in NSPIRES at http://nspires.nasaprs.com/.

    For further information contact Claire Macaulay, Program Administrator for NESSF Earth Science Research, Telephone: (202) 358-0151, E-mail: claire.i.macaulay@nasa.gov or Dolores Holland, Program Administrator for NESSF Heliophysics Research, Planetary Science Research, and Astrophysics Research, Telephone: (202) 358-0734, E-mail: hq-nessf-Space@nasa.gov.
  • Link to full articleNASA and US Air Force reach agreement Release Date: 09/06/2013 An agreement was reached between NASA and the US Air Force concerning the hosting of NASA supplied laser retroreflector arrays onto future GPS satellites. This agreement gives NASA the formal approval to move forward with the GPS Laser Retroreflector Array (GPS-LRA) Project that will supply the retroreflectors for the GPS-III satellites starting with SV-9.

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  • 18th International Workshop on Laser Ranging Logo18th International Workshop on Laser Ranging Release Date: 07/19/2013 Registration and abstract submission for the 18th International Workshop on Laser Ranging are now open. Participants are all requested to fill out these forms by 20 September. The overall schedule in the workshop week, including the opening lectures on Monday morning by Dr J J Degnan and Dr M Fujita, can be found on the workshop website.

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  • California's Chariot Fire affects Monument Peak operationsRelease Date: 07/15/2013 The Chariot Fire in southern California has required the shutdown of operations at NASA's MOBLAS-4 SLR station in Monument Peak. The crew safely evacuated on Monday July 8th and returned July 12th. The station has safely returned to operations. The fire reached within a mile of the station. (Photo courtesy of wildfiretoday.com)

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  • NASA Forms Space Geodesy Working Group
    05/30/2013 NASA has formed the Space Geodesy Working Group to perform fact-finding related to the scientific, technical, and organizational issues associated with the ongoing development of its Space Geodesy Program. The term of service for the Space Geodesy Working Group is three years. The Working Group is tasked to:

    • Conduct semi-annual reviews of the Space Geodesy Program to include reviews of the Program's scientific requirements, strategies, and technical approaches; and
    • Provide technical findings to NASA on its evaluations of and options for resolving program and project challenges following each semi-annual review.

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  • Space Geodesy SLR Request for Information Released
    05/02/2013 The National Aeronautics and Space Administration (NASA) Space Geodesy Project (SGP) is soliciting information to improve its understanding of the interest, capabilities, and Rough Order of Magnitude (ROM) estimates for planning the construction, deployment, and operation of the next generation Space Geodesy (SG) Satellite Laser Ranging (SLR) Stations that will be part of a new NASA’s Space Geodetic Network (SGN). NASA is considering the construction of up to ten new SLR stations that will contribute to the larger Global Geodetic Observing System (GGOS).

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  • 18th International Workshop on Laser Ranging Logo The first announcement of the next International Workshop on Laser Ranging has been issued.Release Date: 04/23/2013 The 18th International Workshop on Laser Ranging is organized so that worldwide scientists and engineers in this and related fields can exchange their views, share opinions on the on-going problems, and navigate the future.

    The theme of this year's workshop is "Pursuing Ultimate Accuracy & Creating New Synergies." In addition to the important topic of maximizing accuracy, this workshop is intended to enhance the potential of laser ranging with the inclusion of activities in relevant fields.

    The workshop will take place November 11-15, 2013 at the Highland Resort Hotel, Fujiyoshida, Japan. More information is available on the workshop website: http://geo.science.hit-u.ac.jp/lw18/.

    Please consider your participation and reserve the week now. The procedures for the registration (including hotel booking) and the abstract submission will be announced in July. Please contact the local organizing committee (Z-LW18@jaxa.jp) for additional information.
  • ITRF2013 Call for Participation
    03/28/2013 Please be informed that the ITRF2013 Call for Participation is now released and could be retrieved at the ITRF web site, using the following link:

    http://itrf.ign.fr/ITRF_solutions/2013/CFP-ITRF2013-27-03-2013.pdf

    In addition to the solicited global solutions from the four space geodesy techniques (to be provided by the Technique Services), we also solicit and encourage the owners of co-location sites to consider conducting new local tie surveys using the most up to date survey methods. Indeed, the local ties available at the ITRS Center for a certain number of co-location sites are now old by 10 to 20 years. In this respect, we would greatly appreciate the contribution of the national mapping and space agencies investing and operating co-location sites, which constitute the main foundation of the ITRF. More details regarding the local tie survey are available in the ITRF2013 CfP.
  • Earth Orientation Animations
    03/01/2013 When you think of the Earth’s orientation, you’d probably imagine something like a globe, where it always rotates around an axis, called the spin axis, defined by the north and south poles. And while this generally makes sense, in reality, the Earth’s orientation is constantly changing very slightly, and this change can be described in three ways. Learn more about how the Earth's orientation changes by watching these animations.

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  • NASA Beams Mona Lisa to Lunar Reconnaissance Orbiter at the Moon
    01/28/2013 Laser communication and ranging experiments were successfully conducted from the satellite laser ranging (SLR) station at NASA Goddard Space Flight Center (GSFC) to the Lunar Reconnaissance Orbiter (LRO) in lunar orbit. The experiments used 4096-ary pulse position modulation (PPM) for the laser pulses during one-way LRO Laser Ranging (LR) operations. Reed-Solomon forward error correction codes were used to correct the PPM symbol errors due to atmosphere turbulence and pointing jitter. The signal fading was measured and the results were compared to the model.

    The Mona Lisa Lasercom to the Moon from NGSLR demonstrates the potential of the SG Network beyond geodesy. The NASA news release was picked up by nearly all the major news outlets. Several members of the NGSLR team were co-authors of the paper which was published online in Optics Express.

    Read the paper in Optics Express
    Read the NASA news release
  • Dr. Henry Plotkin, visits NASA's Next Generation Satellite Laser Ranging (NGSLR) system12/2012 Retired NASA physicist, Dr. Henry Plotkin, visits NASA's Next Generation Satellite Laser Ranging (NGSLR) system in December 2012. As the former Head of the old Optical Systems Branch (Code 524) at NASA Goddard Space Flight Center, Dr. Plotkin led the development of the earliest NASA SLR systems. His team recorded the first laser returns from a retroreflector-equipped artificial satellite (Explorer 22B) almost 50 years ago on October 31, 1964. He is shown here with Jan McGarry in front of the NGSLR system.

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  • Ignite GGOS!
    11/21/2012 The IGS and UNAVCO are sponsoring an evening reception on December 02, 2012 on behalf of the Global Geodetic Observing System (GGOS). A fun, educational, and humorous evening of short, fast-paced presentations will be given by people who are passionate about what they do. There will be plenty of appetizers and a cash bar.

    Ignite GGOS 2012!
    Sunday, December 2nd, at 7:00 pm
    The Westin San Francisco Market Street
    Metropolitan 1
    50 Third Street
    San Francisco, California

    Ignite is an O'Reilly Media concept meant to be fast-paced, creative, and outside-the-box of conventional conference presentations. Ignite GGOS promises to be a fun and light-hearted hour to stimulate your thinking with diverse visions for GGOS and beyond.

    For more information, please contact: IGS Central Bureau, Ignite Coordinator: craddock_AT_jpl.nasa.gov
  • International Technical Laser Workshop 2012 (ITLW-12) 11/19/2012 The ILRS held an International Technical Laser Workshop 2012 (ITLW-12) on "Satellite, Lunar and Planetary Laser Ranging: characterizing the space segment" at the Frascati National Laboratories of the INFN-LNF, Frascati (Rome), Italy on November 5-9, 2012, in conjunction with a one-day Workshop on "ASI-INFN ETRUSCO-2 Project of Technological Development and Test of SLR Payloads for GNSS Satellites". The meeting focused on the laser ranging space segment including retroreflector arrays for Earth orbiting satellites and the moon, with special attention to the expanding role of ranging to GNSS and geosynchronous satellites. Topics also included receivers in space for time transfer experiments (T2L2), one-way ranging to lunar orbiters (LRO) and interplanetary spacecraft (MLA, MOLA), and data relay systems.
  • New ILRS web site released 10/09/2012 The ILRS Central Bureau is pleased to announce the implementation of a new design for the ILRS website, http://ilrs.gsfc.nasa.gov. The redesign process has allowed for a review of the organization of the site and its contents, ensuring information is current and useful. Comments and suggestions are welcome and should be directed to the ILRS web team at ilrs-web@lists.nasa.gov. We would like to acknowledge the efforts of the website development team (Lisa Lee, Mark Torrence, Lori Tyahla, and Carey Noll) as well as members of the Central Bureau and the ILRS community for their contributions to the site content.
  • Space Geodesy Request for Information
    08/30/2012 The National Aeronautics and Space Administration (NASA) is soliciting information to improve its understanding of the interest, capabilities, and Rough Order of Magnitude (ROM) estimates for planning the construction, deployment, and operation of the next generation Space Geodesy (SG) stations that will be part of the upcoming NASA’s Space Geodetic Network (SGN). NASA is considering the construction of up to ten new or upgraded stations that will contribute to the larger Global Geodetic System (GGOS).

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  • Staff Profile: Jan McGarry, Mathematician
    08/16/2012 Mathematician Jan McGarry discusses the science and history of Satellite Laser Ranging (SLR), her role in developing the Next Generation Satellite Laser Ranging system, and her career at NASA's Goddard Space Flight Center.

    Watch video
  • NGSLR Optical Bench Laboratory Build Status
    08/15/2012 The design and laboratory build of the new Optical Bench has been completed. Assembled at a GSFC Building 33 clean room laboratory, the new bench offers an improved optical layout, incorporates alignment lasers, and uses monitoring cameras for more efficient alignments. A beam profiler has been incorporated allowing verification of the transmit beam divergence and doubles as a means of monitoring the pointing of the laser. The new design now supports motorized optical mounts to enable automated operations. The Optical Bench was upgraded with a higher power, shorter pulse width laser for more robust daylight GPS ranging along with the use of high power coatings on the transmit optics to handle the extra energy. The original Optical Bench was designed for laser energies up to 350 microjoules while the new Optical Bench is designed to handle energies up to 3,000 microjoules. The laboratory build of the new Optical Bench allowed engineers to test the new layout and develop alignment procedures for the enhanced design. While the build was taking place in the laboratory, system development efforts were allowed to continue at the NGSLR. Completed in July, the new bench is in the process of being moved to the NGSLR. Pictures of the new bench undergoing the laboratory build are shown.

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  • Time-lapse video of VLBI2010 Installation at GGAO
    08/14/2012 Time lapse video showing the construction of the VLBI2010 antenna at NASA Goddard Geophysical and Astronomical Observatory GGAO, September 15 through October 12, 2010.

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  • NGSLR 2012 Summer Interns
    08/05/2012 SGP staff mentored eight interns during the summer of 2012.

    Visit 2012 Interns page
  • Staff Profile: Carey Noll, Computer Scientist
    08/02/2012 Computer scientist Carey Noll talks about her job as manager of the Crustal Dynamics Data Information System (CDDIS), the applications of her work for various space geodesy techniques such as GPS, and her career at NASA's Goddard Space Flight Center.

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  • Staff Profile: Chopo Ma, Space Geodesist
    07/12/2012 Space geodesist Chopo Ma explains the science of Very Long Baseline Interferometry (VLBI): using radio emissions from distant galaxies to create a precise reference frame for the Earth.

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  • "Sizing Up Earth" for iPad
    07/10/2012 Read an introduction to Space Geodesy using the NASA Visualization iPad app.

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    Download NASA Visualization iPad app
  • Staff Profile: Stephen Merkowitz, Project Manager
    07/05/2012 Project manager Stephen Merkowitz talks about his work with NASA's Space Geodesy Project, including a brief overview of the four fundamental techniques of space geodesy: GPS, VLBI, SLR, and DORIS.

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  • NASA Explains Why Clocks Will Get an Extra Second on June 30
    06/29/2012 If the day seems a little longer than usual on Saturday, June 30, 2012, that's because it will be. An extra second, or "leap" second, will be added at midnight to account for the fact that it is taking Earth longer and longer to complete one full turn—a day—or, technically, a solar day.

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  • Using Quasars to Measure the Earth: A History of VLBI
    06/21/2012 VLBI, or Very Long Baseline Interferometry, is a technique that uses multiple radio telescopes to very precisely measure the Earth's orientation. It was originally invented back in the 1960s to take better pictures of quasars, but scientists soon found out that if you threw the process in reverse, you could measure how the ground beneath the telescopes moves around, how long days really are, and how the Earth wobbles on its axis as it revolves around the sun!

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  • NGSLR Makes its First Successful Daylight Ranging to a GNSS Satellite
    04/30/2012 NGSLR made its first successful daylight ranging to a GNSS satellite (GLONASS-109) on April 2, 2012 at approximately 7pm EDT, about 30 minutes before sunset. The system obtained satellite returns immediately after laser turn-on. The satellite was tracked for an hour, down below 35 degrees elevation. The pass was strong enough for real-time signal processing to find much of the signal. A second daylight GNSS pass on GLONASS-115 was obtained on April 3, 2012 at appoximately 2pm EDT.

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  • NASA Response on Legacy Stations Submitted and Accepted
    03/26/2012 The The NASA response on legacy stations submitted to the GGOS Bureau for Networks and Communication Call for Participation was recently accepted.
  • NASA Pinning Down "Here" Better Than Ever
    02/23/2012 NASA is helping to lead an international effort to upgrade the four systems that supply crucial location information in pinpointing where "here" is.

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  • VLBI2010 Demonstration with Full Configuration at GGAO
    01/20/2012 VLBI2010 successfully conducted 4-band fringe test and emonstrated antenna aperture efficiency, feed horn sensitivity, and backend data system components meet baseline VLBI2010 requirements.

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  • Installation of GNSS deep drilled brace monuments
    01/20/2012 The installation of GNSS deep drilled brace monuments at GGAO was completed. Multi-Constellation GNSS receivers, antennae/radomes, and supporting data collection computer have been installed at GGAO and are operating and actively collecting data. Both GNSS receivers are Delta-series units from Javad.

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