The GEO6 project aims at fostering possible novel applications within the scientific UC of GNSS signals, and particularly of GalileoHP G72-102SA Battery.
The Galileo optical experiment
In December 1992 during Galileo’s second gravity assist planetary flyby of Earth, HP G62-144DX Battery another groundbreaking yet almost entirely unpublicized experiment was done using Galileo to assess the possibility of optical communication with spacecraft by detecting pulses of light from powerful lasers which were to be directly imaged by Galileo’s CCD. The experiment, dubbed Galileo OPtical EXperiment or GOPEX, used two separate sites to beam laser pulses to the spacecraft, HP G62-145NR Batteryone at Table Mountain Observatory in California and the other at the Starfire Optical Range in New Mexico. The Table Mountain site used a frequency doubled Neodymium-Yttrium-Aluminium Garnet (Nd:YAG) laser operating at 532 nm with a repetition rate of ~15 to 30 Hz and a pulse power (FWHM) in the tens of megawatts range, HP G62-147NR Batterywhich was coupled to a 0.6 meter Cassegrain telescope for transmission to Galileo; the Starfire range site used a similar setup with a larger transmitting telescope (1.5 m). Long exposure (~0.1 to 0.8 s) images using Galileo’s 560 nm centered green filter produced images of Earth clearly showing the laser pulses even at distances of up to 6,000,000 km. HP G62-149WM BatteryAdverse weather conditions, restrictions placed on laser transmissions by the U.S. Space Defense Operations Center (SPADOC) and a pointing error caused by the scan platform acceleration on the spacecraft being slower than expected (which prevented laser detection on all frames with less than 400 ms exposure times) all contributed to the reduction of the number of successful detections of the laser transmission to 48 of the total 159 frames taken. HP G62-150EE BatteryNonetheless, the experiment was considered a resounding success and the data acquired will likely be used in the future to design laser “downlinks” which will send large volumes of data very quickly, from spacecraft to Earth. The scheme is already being studied (as of 2004) for a data link to a future Mars orbiting spacecraft. HP G62-150EF Battery