Satellite laser ranging

Satellite laser ranging (SLR) is a method to measure the distance to satellites in a geocentric orbit. It consists of an astronomical observatory equipped with a laser that sends ultrashort pulses of light. The pulses hit the satellite and bounce back to be caught by the station, which measure the round trip time with the speed of light formula. These measurements are instantaneous and with millimeter level precision, which can be accumulated to provide accurate measurement of orbits and a host of important scientific data. Some satellites have retroreflectors, but the method also works on space debris.

Satellite laser ranging is a proven geodetic technique with significant potential for important contributions to scientific studies of the earth/atmosphere/ocean system. It is the most accurate technique currently available to determine the geocentric position of an Earth satellite, allowing for the precise calibration of radar altimeters and separation of long-term instrumentation drift from secular changes in ocean topography.

Its ability to measure the variations over time in Earth's gravity field and to monitor motion of the station network with respect to the geocenter, together with the capability to monitor vertical motion in an absolute system, makes it unique for modeling and evaluating long-term climate change by:

  • providing a reference system for post-glacial rebound, plate tectonics, sea level and ice volume change
  • determining the temporal mass redistribution of the solid earth, ocean, and atmosphere system
  • determining Earth orientation parameters, such as Earth pole coordinates and length-of-day variations
  • determining of precise satellite orbits for artificial satellites with and without active devices onboard
  • monitoring the response of the atmosphere to seasonal variations in solar heating.

SLR provides a unique capability for verification of the predictions of the theory of general relativity, such as the frame-dragging effect.

SLR stations form an important part of the international network of space geodetic observatories, which include VLBI, GPS, DORIS and PRARE systems. On several critical missions, SLR has provided failsafe redundancy when other radiometric tracking systems have failed.

This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.