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Overview

Satellite Laser Ranging (SLR) and Lunar Laser Ranging (LLR) use short-pulse lasers and state-of-the-art optical receivers and timing electronics to measure the two-way time of flight (and hence distance) from ground stations to retroreflector arrays on Earth orbiting satellites and the Moon. Scientific products derived using SLR and LLR data include precise geocentric positions and motions of ground stations, satellite orbits, components of Earth’s gravity field and their temporal variations, Earth Orientation Parameters (EOP), 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 can perform very accurate time transfer between sites far apart. Laser ranging activities are organized under the International Laser Ranging Service (ILRS) which provides global satellite and lunar laser ranging data and their derived data products to support research in geodesy, geophysics, Lunar science, and fundamental constants. This includes data products that are fundamental to the International Terrestrial Reference Frame (ITRF), which is established and maintained by the International Earth Rotation and Reference Systems Service (IERS). The ILRS develops the necessary global standards/specifications for laser ranging activities and encourages international adherence to its conventions.

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Highlights

Passing of James Leroy Long (1955 - 2019)Release Date: 09/30/2019The Space Geodesy Project and the ILRS community is mourning the loss of our dear friend and colleague James Leroy Long who passed away on September 21, 2019 from prostate cancer complications.

Jim was a leader and essential contributor to the nation's space geodesy programs over the past 40 years. Jim began his career in 1978 as a Commissioned Officer within the US Department of Commerce NOAA Corps. For two years, Jim was the Party Chief for the transportable 5-meter antenna system collecting Very Long Baseline Interferometry (VLBI) data in support of the NASA Crustal Dynamics Program and the NOAA National Crustal Motion Network. These measurements led to the first measurements of continental drift. Jim also spent several years on mobile field duty for the U.S. Coast & Geodetic Survey performing precise horizontal control surveys and special project surveys.

Read more about Jim Long...

2019 ILRS Technical WorkshopRelease Date: 08/06/2019The 2019 ILRS Technical Workshop will take place in Stuttgart, Germany, October 21-25. If you plan to attend, please register by August 15 (next Thursday) on the workshop website:

https://ilrsworkshop2019.besl-eventservice.de/front/index.php

If you have any trouble registering, please send an email to ilrs.workshop@dlr.de.

If you plan to present at the workshop, we ask that you also upload your abstract as soon as possible so we can commence planning the program.

The ILRS is looking forward to seeing you all in Stuttgart!

GNSS Tracking StrategyRelease Date: 08/01/2019 The ILRS has been working with the IGS and other interested parties to settle on a GNSS tracking strategy that would satisfy both mission and user requirements. For some applications, users want denser tracking on a few satellites. For other applications, users want some tracking on the full complex of GNSS satellites, even if that tracking is sparse. In addition, there are also requests for focused campaigns, in particular, for tracking GNSS satellites while going through Earth shadow to study the effects of radiation pressure. We presently have over 60 GNSS satellites (GLONASS, Galileo, BeiDou) on the ILRS roster. More will be added in the near future. The total could reach nearly 100 when GPS is added in the 2024 timeframe.

The strategy that the ILRS has agreed to implement is the following:

GNSS tracking will continue to be prioritized with the other ILRS satellites by the standard ILRS priority scheme (by altitude and inclination);
Four GNSS satellites will be identified by each constellation (Galileo, GLONASS, and BeiDou) for intensive tracking, with three sectors (at least 2 normal points each) spaced widely apart over the pass. If stations cannot obtain three sectors they should try to get two sectors. These four satellites per constellation would be selected by the constellation and would have the highest priority among the GNSS satellites.
All of the remaining GNSS satellites would be tracked by the stations on an as time available basis; selection of targets should be determined by the stations for data yield, but stations are asked to try to diversify among all three constellations because we need some data on all three.
There may be some special tracking periods (e.g. satellite eclipses, etc.) that may need other scheduling.

The agreed high priority GNSS satellites are:

BeiDou3-M2, 3-M3, 3-M9, and 3-M10
Galileo-102, -202, -209, -210
GLONASS-131, -134, -138, and -139

The ILRS asks that you implement this new priority strategy in your tracking operation, by August 15, 2019. Please contact the ILRS CB if you have any questions.

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Recent News

The Jason-2 mission has ended - The Jason-2/Ocean Surface Topography Mission (OSTM), the third in a U.S.-European series of satellite missions designed to measure sea surface height, successfully ended its science mission on Oct. 1. NASA and its mission partners made the decision to end the mission after detecting deterioration in the spacecraft's power system.

Read more about the Jason-2 mission...

Passing of James Leroy Long (1955 - 2019) - The Space Geodesy Project and the ILRS community is mourning the loss of our dear friend and colleague James Leroy Long who passed away on September 21, 2019 from prostate cancer complications.

Jim was a leader and essential contributor to the nation's space geodesy programs over the past 40 years. Jim began his career in 1978 as a Commissioned Officer within the US Department of Commerce NOAA Corps. For two years, Jim was the Party Chief for the transportable 5-meter antenna system collecting Very Long Baseline Interferometry (VLBI) data in support of the NASA Crustal Dynamics Program and the NOAA National Crustal Motion Network. These measurements led to the first measurements of continental drift. Jim also spent several years on mobile field duty for the U.S. Coast & Geodetic Survey performing precise horizontal control surveys and special project surveys.

Read more about Jim Long...

New Guidelines for prosposing and planning International Workshops on Laser Ranging and ILRS Specialized/Technical Workshops - The ILRS sponsors International Workshops on Laser Ranging (IWLR) which are typically held every two years. In addition, the ILRS organizes focused technical or specialized workshops in years between the International Workshops on Laser Ranging. Recently, the ILRS has created guidelines for the community to propose future workshops and for the ILRS in planning these workshops.

Lightning strikes the McDonald Laser Ranging Station (MLRS) in Texas - Lightning struck the McDonald Laser Ranging Station (MLRS) in Texas on September 12, 2019 rendering it inoperable. The SGP is currently building a next generation SGSLR station next to the MLRS, and has decided to not repair the 37-year-old MLRS. The MLRS first started operating in 1982 and quickly became a premiere satellite and lunar laser ranging station. Data from this station was used for the most stringent tests of General Relativity, studies of the interior structure of the moon, and countless other geodetic and spacecraft tracking applications. The SGP looks forward to continuing the legacy of laser ranging from the McDonald Observatory and entering a new chapter with the recently completed VGOS station located just down the hill from the MLRS.

2019 ILRS Technical Workshop - The 2019 ILRS Technical Workshop will take place in Stuttgart, Germany, October 21-25. If you plan to attend, please register by August 15 (next Thursday) on the workshop website:

https://ilrsworkshop2019.besl-eventservice.de/front/index.php

If you have any trouble registering, please send an email to ilrs.workshop@dlr.de. If you plan to present at the workshop, the ILRS asks that you also upload your abstract as soon as possible so we can commence planning the program. We are looking forward to seeing you all in Stuttgart!