Welcome
NGSLR Greenbelt, MD
Highlights
CDDIS unavailable November 30-December 01 for transition to new systemsRelease Date: 11/17/2016On November 30, 2016 at 13:00 UTC, CDDIS will terminate all services (ftp, CDDIS/ILRS/SGP websites, data deliveries) as we transition to all new hardware and facilities. We are projecting about 24 hours to fully move to our new facilities and ensure all operations are back to normal. As such, all users need to plan on a 24+ hour disruption of service to the CDDIS archive with resumption of normal operations no earlier than December 01, 2016 at 17:00 UTC.
In summary the following will take place:
- 30 November 2016 at 13:00 UTC – All current production services (ftp, http, etc) will be shutdown.
- 01 December 2016 at 17:00 UTC – all web and anonymous ftp access is restored for access to the archive. NOTE: restoration could occur sooner but no guarantees are made.
- Currently used addresses, e.g., cddis.nasa.gov or cddis.gsfc.nasa.gov, will continue to work as before the transition. However, if you are using a numeric IP address to access any CDDIS resources your scripts will fail as all current IP addresses will change during the transition.
- 02 December 2016 – All CDDIS operations should be returned to normal service.
- IGS: http://www.igs.org/about/data-centers
- ILRS: http://ilrs.gsfc.nasa.gov/data_and_products/data_centers/index.html (check before November 30!)
- IVS: http://ivscc.gsfc.nasa.gov/about/org/components/dc-list.html>
- IDS: http://ids-doris.org/data-products/info.html
Workshop website for the 20th International Workshop on Laser Ranging 2016 in PotsdamRelease Date: 11/09/2016A dedicated ILRS website for the 20th International Workshop on Laser Ranging 2016 in Potsdam is now available at http://cddis.gsfc.nasa.gov/lw20/ which also contains instructions for preparing contributions to the proceedings. Please follow the instructions and be aware of the deadline January 31, 2017.
Ajisai celebrates 30 years in space Release Date: 08/13/2016
JAXA launched the Ajisai spacecraft from the Tanegashima Space Center on August 13, 1986 at 05:45 JST. Ajisai is Japan’s first geometric satellite. Read more about the anniversary celebration.
User Profile: Dr. Erricos C. Pavlis Release Date: 08/11/2016
NASA Earthdata has published a user profile of Dr. Erricos Pavlis as part of their "Who uses NASA Earth science data?" series.
LARES + LAGEOS 1&2 Lense-Thirring results selected as EPJ-C coverRelease Date: 07/19/2016
The article, "A test of general relativity using the LARES and LAGEOS satellites and a GRACE Earth gravity model," (Ciufolini et. al.) has been published in the March 2016 issue of the European Physical Journal-C. Furthermore, a figure from this paper has been selected for the cover of that issue.
NASA Space Geodesy Data for Precise Orbit Determination of Altimeter Satellites Webinar (NASA Earthdata webinar series)Release Date: 06/29/2016
Over the last 25 years, ocean radar altimeter satellites have revolutionized our understanding of the world’s oceans. Today six altimeter satellites from different national and international space agencies synoptically measure the ocean surface topography in order to determine how the ocean surface changes with time. The heart of the altimeter measurement is the precise determination of the orbit reference which is used as the basis from which the changes in the ocean surface are determined. We now routinely determine the orbits of the joint NASA/CNES/NOAA/EUMETSAT missions Jason-2 and Jason-3 with a radial RMS precision of 1 cm.
This webinar describes how we can compute these orbits with such accuracy, and will further outline how these computations rely directly and indirectly on a suite of international Space Geodesy data as well as data from different NASA satellites.
Now 40, NASA's LAGEOS Set the Bar for Studies of EarthRelease Date: 05/04/2016
On May 4, 1976, NASA launched a cannonball-shaped satellite that transformed studies of Earth’s shape, rotation and gravity field.
LAGEOS – short for Laser Geodynamic Satellite – was the first NASA orbiter dedicated to the precision measurement technique called laser ranging. With it, scientists have measured the movement of Earth’s tectonic plates, detected irregularities in the rotation of the planet, weighed it, and tracked small shifts in its center of mass.
Small deviations in the satellite’s orbit were used to develop early models of Earth’s gravitational field. Further perturbations in the orbit helped explain how sunlight heating small objects can affect their orbits, including near-Earth asteroids.
Read more...
The GREAT experimentRelease Date: 04/27/2016
The unplanned eccentric orbit of Galileo-201 and -202 provides a unique opportunity to study the behavior of on-board clocks and the gravitational redshift predicted by General Relativity. The Galileo-201 and -202 satellites, the first two Fully Operational Capability (FOC) satellites, were launched on August 22, 2014. Due to technical problems with the launch, these satellites remain in an elliptical orbit, which is not useful for the Galileo operations.
Colleagues with the Galileo mission have proposed a one-year, ESA funded experiment, GREAT (Galileo gravitational Redshift Experiment with eccentric sATellites) during which the SLR will provide periods of intensive tracking on Galileo-201. The GREAT experiment will begin May 1, 2016. The stations in the ILRS network are asked to support this experiment.
