18 December 2006 – Artemis, the European Space Agency’s Advanced Relay and Technology Mission Satellite, successfully relayed optical laser links from an aircraft in early December. These airborne laser links, established over a distance of 40,000 km during two flights at altitudes of 6,000 and 10, 000 metres, represent a world first. It has clearly demonstrated the feasibility of an optical link between an airborne carrier and a geostationary satellite.
The relay was set up through six two-way optical links between a Mystère 20 equipped with the airborne laser optical link LOLA (Liaison Optique Laser Aéroportée) and the SILEX laser link payload on board ARTEMIS in its geostationary orbital position at 36,000 km altitude: a feat equivalent to targeting a golf ball over the distance between Paris and Brussels.
These tests were made by Astrium SAS (France), the prime constructor for both LOLA and SILEX, as part of the airborne laser optical link programme conducted by the DGA (French MoD procurement agency) from its Flight Test Centre at Istres, in the south of France. The ESA ground station of Redu, Belgium, also contributed to this success by managing the Artemis SILEX payload operations.
Previously, in November 2001, Artemis made a world premiere by establishing a laser link with the French Earth Observation satellite SPOT-4: imaging data was sent by SPOT-4 using a laser beam as signal carrier to Artemis and from there by radio waves to the ground. This unprecedented link-up between satellites in space was done in the framework of the SILEX development, an innovative payload which provides a laser beam as a data signal carrier.
More recently, since November 2005, Artemis has been relaying optical signals from KIRARI, the Japanese Optical Intersatellite Communications Engineering Test Satellite. This first ever two-way optical communication illustrated the value of this technology for the development of future Earth observation systems.
Optical technology has several advantages for data relay applications, including the capability to provide high data rates with low mass, low power terminals, combined with secure, interference-free communications. Earth observation can truly benefit from this new way of transmitting data around our planet.
On a daily basis Artemis is also relaying data in the Ka-band from Envisat, the ESA Earth observation satellite, providing, since 2002, a comprehensive view of the Earth’s oceans, land, atmosphere and ice caps.
– About Artemis
Artemis was launched on 12 July 2001 on an Ariane 5 from Europe’s spaceport in Kourou, French Guiana. Artemis carries three sophisticated payloads for the fulfilment of navigational, mobile communication and data relay missions over the next 10 years:
– The provision of voice and data communications between mobile terminals, mainly for trucks, trains or boats in remote areas of Europe and North Africa, as well as on the Atlantic.
– Performing a key role within Europe’s EGNOS satellite Navigation System by broadcasting enhanced GPS and Glonass signals for use by civilian ‘safety critical’ transport and navigational services.
– The provision of inter-orbit satellite links using advanced S and Ka band frequencies and laser technology.
As the world’s first civil inter-satellite data relay system to use lasers, it has the capability of transmitting data between terminals at a rate of 50 megabits per second and puts Europe at the forefront of optical space communications. It facilitates the transmission of large amounts of data from low Earth orbit satellites to smaller ground terminals.
The satellite’s data relay systems, which include a sophisticated SILEX (Semi-conductor laser Inter-satellite Link EXperiment) laser and SKDR payloads, allows Earth observation data from other satellites such as France’s Spot 4 and ESA’s Envisat, to be transmitted much faster via Artemis directly to the relevant Earth-based ground stations.
This has far reaching implications for Earth monitoring, particularly in times of crisis such as natural disasters like flooding or earthquakes when time is of the essence to avoid greater catastrophe or risk to human life.