Europe's new Galileo navigation satellites have been measured for the first time by Chile’s Concepción. Measurement of the satellite distance with subcentimetre accuracy has been achieved by establishing laser contact with the satellites at an altitude of 23,230 km.
The world's first laser ranging to the first Galileo satellite was accomplished using a near-infrared laser beam, by the Transportable Integrated Geodetic Observatory, TIGO, in Concepción, on 27 November at 02:45 GMT; and to the second satellite after two days at 10:05 GMT.
The laser ranging was performed similar to a planetary-scale video game, operating from orbital predictions obtained through the Navigation Office at ESA’s European Space Operations Centre, Darmstadt, Germany. After calibrations of their laser using Europe's first test navigation satellite called GIOVE-A, the TIGO team directed by Michael Häfner and Marcos Avendaño, focused with their laser and fired.
Similar to advanced satellites, the Galileo satellites are fixed with reflectors that reverts the laser pulse back to its source of origin. An ultra-precise timer measures the time taken by the laser to return to the ground. The light speed is standardized, so that the satellite’s distance can be calculated with better accuracy than a centimeter.
Laser ranging, besides being used for precise orbit determination of satellites, is also utilized for satellite instruments calibration, enabling contributions to the International Terrestrial Reference Frame and analyzing the ground’s motion because of tectonic plate dynamics. The distance of the moon from the earth can also be calculated.
Source: http://www.esa.int/