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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

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.

We are looking forward to seeing you all in Stuttgart!

Journal of Geodesy Special Issue on Laser RangingRelease Date: 07/23/2019Several peer-reviewed Journal of Geodesy articles were recently published online at the journal site. These are all part of the Special Issue on Laser Ranging which is preparation. Several more articles are in the review process and upon completion the printed version will be published.

In the meantime we invite you to peruse all of these with the latest information on Laser Ranging and the ILRS.

Introductory and Refresher Course on Satellite and Lunar Laser RangingRelease Date: 07/11/2019The ILRS has scheduled a one-day introductory course to give non-practitioners in SLR an opportunity to broaden their knowledge about laser ranging to Earth-orbiting satellites and the Moon. The course will also provide those with some experience in the field an opportunity to refresh and strengthen their knowledge and increase their appreciation of this powerful measurement technique that supports geoscience and applications. The course is scheduled for Sunday, October 20, 2019, in Stuttgart, Germany, just prior to the 2019 ILRS Technical Workshop. The program for this one-day "SLR School" is available.

Talks will be given in a tutorial format, with time for questions and discussion. Interested parties can attend the school with or without participating in the Workshop. Attendees will be charged an entrance fee of 30 Euros to cover lunch and breaks.

Tutorials will differ in length depending on the topic, but each session should leave ample time for questions and discussion. Seminars will be given at the level of a non-expert, recognizing that we expect people to attend who are not currently working in the field, but are curious, as well as people who are newly involved in laser ranging, but need to broadening their current level of understanding.

The one-day SLR School will be a great way for attendees to get an overview of an important component of the space geodesy measurement constellation. Please see the attached PDF for the topics to be covered in the program. Participants in the 2019 ILRS Technical Workshop can indicate their plans to attend the SLR School during registration (see http://dlr.de/ilrs2019). Those wishing to attend only the SLR School should contact the workshop’s local organizing committee (ilrs.workshop@dlr.de); arrangements are being made for payment of the one-day fee.

This one-day event is an opportunity for participants to get an overall view of satellite laser ranging and is the first time that such a school has been offered. The school will be held at the:

Pullman Stuttgart Fontana Hotel
Vollmoellerstraße 5, 70563 Stuttgart, Germany

More Information on hotels, transportation, etc., is available on the workshop website at: http://dlr.de/ilrs2019.

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Recent News

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, we ask 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!

Results of the 2019 Etalon-1 and -2 tracking campaign relased - The results from the actual data analysis of the Etalon campaign period, focusing on the EOP improvement have been collected. Data from the same timeframe in 2018 were reanalyzed in order to have results compared to exactly the same IERS C04 series. As can be seen in this report, the additional Etalon data makes a significant difference, bringing the ILRS EOP product a lot closer to the "final" IERS series (which is ∼90% a GNSS product). The ILRS Analysis Coordinators have requested that the network do their best to increase their collection of Etalon data on a permanent basis.

Updated data screening process at the ILRS Operations Centers (OCs) at EDC and NASA - The ILRS Operations Centers (OCs) at EDC and NASA are updating their data screening process in order to coordinate data quality control (QC) and provide feedback on data issues to the stations. Incoming data will be screened and characterized as:

"errors" if they will adversely impact the quality of the data and the derived data products (e.g., invalid date, invalid satellite, erroneous calibration, etc.)
"warnings" if the impact on the quality of the data is minor, or if there are format errors that make processing or QC evaluation more difficult.

Data that are marked as having errors will not be submitted to the ILRS Data Centers at EDC and CDDIS. Data marked as having warnings will be submitted.

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Stephen Merkowitz now the chair of the Missions Standing Committee - Effective August 01, 2019, Stephen Merkowitz (NASA GSFC) will chair the ILRS Missions Standing Committee, with Toshi Otsubo (Hitotsubashi University and former chair) serving as co-chair.

Reflectors placed on the moon by Apollo 11 astronauts 50 years ago continue to provide fresh lunar laser ranging data - Fifty years ago, Neil Armstrong, Buzz Aldrin and Michael Collins left behind arrays of prisms that reflect light back toward its source; the Apollo 14 and 15 astronauts also did so. Four telescopes at observatories in New Mexico, France, Italy and Germany fire lasers at them, measuring the time that it takes for a laser pulse to bounce off the reflectors and return to Earth. This allows the distance to be measured to within a fraction of an inch (a few millimeters), and scientists at the Jet Propulsion Laboratory analyze the results. Lunar laser ranging measurements have deepened our understanding of the dance between the Moon and Earth.

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