NGSLR Greenbelt, MD


Ajisai satelliteAjisai 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.

Dr. Erricos PavlisUser 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.

March 2016 cover of the European Physical JournalLARES + 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.

Earthdata logoNASA 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.

LAGEOS satelliteNow 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.


galileo satelliteThe 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.

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