NASA will be performing network maintenance on Wednesday, November 20, 2024, between 11:00 AM EST and 1:00 PM EST (16:00 to 18:00 UTC). There will be two periods of about five minutes of disruption. During these peroids, the ILRS website will be unavailable during the outages. If you experience problems outside this window, contact support-cddis@nasa.gov.

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ILRS Technology and Engineering Activities

The service collects, merges, analyzes, archives and distributes Satellite Laser Ranging (SLR) and Lunar Laser Ranging (LLR) observation data sets to satisfy the objectives of scientific, engineering, and operational applications and programs. The basic observables are the precise two-way time-of-flight of an ultrashort laser pulse to a retroreflector array on a satellite or the Moon and the one-way time of flight to a space borne receiver (transponder). These data sets are made available to the community and are also used by the ILRS to generate fundamental data products, including: accurate satellite ephemerides, Earth orientation parameters, three-dimensional coordinates and velocities of the ILRS tracking stations, time-varying geocenter coordinates, static and time-varying coefficients of the Earth's gravity field, fundamental physical constants, lunar ephemerides and librations, and lunar orientation parameters.

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