Europe Launches Satellite to Speed Up Space Communications

Tonight’s launch of EDRS-A is a milestone for laser relays in orbit.

It's showtime: The Eutelsat-9B satellite with its EDRS-A payload undergoes testing at Airbus Defence and Space in Toulouse, France. (Airbus Defence and Space)
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Eutelsat 9B, scheduled to launch this evening from Kazakhstan on a Russian Proton rocket, looks at first glance like a typical commercial communications satellite:  a standard Eurostar E3000 bus and solar panels, with 66 microwave radio transmitters, all built to beam high-quality satellite TV to homes across Europe.

But this time an unusual, extra piece of hardware will be hitching a ride to high geosynchronous orbit. A laser communication system called the European Data Relay Satellite A (EDRS A), attached to the Eutelsat as a hosted payload, marks Europe’s biggest step yet toward revolutionizing communications in space.

Satellites typically communicate with Earth at radio and microwave frequencies. But radio has some serious drawbacks. Depending on the wave’s amplitude and frequency, it can bounce off water and other common atmospheric particles. Radio is limited in the amount of information it can carry, and given the increasing amount of data collected by modern sensors, that becomes a serious drawback. New Horizons, for instance, gathered data over weeks as it flew past Pluto and Charon; it will take over 18 months to send all the data back.

The answer is to use shorter waves. Microwaves and infrared, the next bands up in the electromagnetic spectrum, can carry more data but are also subject to interference. The next step is optical communication, using lasers—tight beams of visible light that don’t disperse as easily, making them ideal for long-distance communication.

Enter EDRS-A, the first of three planned lasers in geostationary orbit. EDRS-A will receive laser data from two spacecraft already in orbit, the European Sentinel weather satellites, and relay the data down to the ground via laser. If it works—and there’s no reason it shouldn’t—the test will boost the space data transmission rate by an order of magnitude. And that will come in handy for future interplanetary probes as well as satellites in Earth orbit.

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