December 23rd, 2006
From plane to satellite by laser
If you ever used an Internet connection in a plane, you probably think that it's easy to communicate between an aircraft and a satellite. This is true for 'traditional' data relay applications. But recently, a European Space Agency (ESA) satellite relayed optical laser links from an aircraft over a distance of 40,000 km for the first time. It remains to be seen if this kind of optical technology can be used for routine applications. However, it is attractive because it provides interference-free communications.
Here is the first paragraph of the ESA news release.
Artemis, the European Space Agency 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 6000 and 10 000 metres, represent a world first.
I don't really understand what the ESA means. The first sentence implies signals sent from a plane while the second one apparently means that the optical signals went from one plane to another via satellite. If you know about this ESA experiment, drop me a note.
As technical details are scarce, let's look at some illustrations. Below is an artist's rendition of the Artemis and SPOT 4 satellites communicating via the SILEX laser link system onboard Artemis (Credit: ESA/J.Huart). Here is a link to a larger version.
Last year, Artemis already successfully established an optical data relay link with OICETS (December 9, 2005). OICETS, which stands for "Optical Inter-orbit Communications Engineering Test Satellite," is the official name for KIRARI, a satellite launched by the Japan Aerospace Exploration Agency (JAXA). Below is an artist's rendition of the optical data relay link between OICETS and Artemis (Credit: JAXA).
So we now know that optical links between an airborne carrier and a geostationary satellite are possible, but what will they be useful for?
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.
From what I'm reading between the lines, it looks like ordinary people will not benefit from this technology before years.
Sources: European Space Agency news release, via EurekAlert!, December 18, 2006; and various websites
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