In 2006, Japan carried out the first LEO-to-ground laser-communication downlink from JAXA's OICETS LEO satellite and NICT's optical ground station. This diode-pumped infrared neodymium laser, designed as a laser altimeter for a Mercury orbit mission, was able to communicate across a distance of 24,000,000 km (15,000,000 mi), as the craft neared Earth on a fly-by. In May 2005, a two-way distance record for communication was set by the Mercury laser altimeter instrument aboard the MESSENGER spacecraft. Since 2005, ARTEMIS has been relaying two-way optical signals from KIRARI, the Japanese Optical Intersatellite Communications Engineering Test Satellite. Achieving 50 Mbps across 40,000 km (25,000 mi), the distance of a LEO-GEO link. In November 2001, the world's first laser intersatellite link was achieved in space by the European Space Agency (ESA) satellite Artemis, providing an optical data transmission link with the CNES Earth observation satellite SPOT 4. The first successful laser-communication link from space was carried out by Japan in 1995 between the JAXA's ETS-VI GEO satellite and the 1.5 m (4 ft 11 in) National Institute of Information and Communications Technology (NICT) 's optical ground station in Tokyo achieving 1 Mbit/s. In 1992, the Galileo probe proved successful one-way detection of laser light from Earth as two ground-based lasers were seen from 6,000,000 km (3,700,000 mi) by the out-bound probe. ![]() On 20 January 1968, the television camera of the Surveyor 7 lunar lander successfully detected two argon lasers from Kitt Peak National Observatory in Arizona and Table Mountain Observatory in Wrightwood, California. Laser-based optical communication has been demonstrated between the Earth and Moon and it has the potential to bridge interplanetary distances of millions of kilometers, using optical telescopes as beam expanders. In outer space, the communication range of free-space optical communication is currently of the order of hundreds of thousands of kilometers. The main advantage of using laser communications over radio waves is increased bandwidth, enabling the transfer of more data in less time. Communication may be fully in space (an inter-satellite laser link) or in a ground-to-satellite or satellite-to-ground application. Laser communication in space is the use of free-space optical communication in outer space. ![]() This article may need to be rewritten to comply with Wikipedia's quality standards.
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