Talking to Shooting Stars With Meteor Burst

Have you ever talked to a shooting star?

Those brilliant trails of light, falling through the atmosphere, are telling power companies about the depths of rivers, and poor countries about the quality of their soil. They're even telling a California company where to find its ambulances.

This isn't a fairy tale. It's meteor burst communications, one of the best-kept secrets in the communications industry. For the past 50 years, meteor burst systems have used the ionized trails of evaporating space rocks as a poor man's satellite, bouncing radio signals off them to receivers located more than 1,000 miles away.

Meteor burst is cheaper than satellites and more reliable than cellular technology, but it has its downsides: it's slow, and only works in brief spurts with delays of seconds or minutes between transmissions.

"It's never going to be something that everybody uses — you couldn't use it for a continuous voice call," said Carl Baum, a professor at Clemson University who has studied meteor burst systems.

Talking to Shooting Stars

Earth is continually moving through space, and space is dusty. Space rocks are continually burning up in our upper atmosphere, turning into trails of ionized gases. Those gases can reflect radio signals — so if you send a radio signal to the right spot at the right time, you can bounce a radio signal as far as 1,400 miles away.

(The low-frequency waves used by meteor burst systems normally have a 90-mile range, much longer than cellular phone waves. They need the range because the meteors they seek can be more than 60 miles up in the sky.)

A typical commercial or military meteor burst setup involves a large base station with about 5,000 watts of radio power and eight 20-foot antennas, and several remote radios with about 100 watts of power apiece. The base station continually transmits a carrier tone toward various parts of the sky, and the remote radios sit in receiving mode.

When a meteor comes into range, the carrier tone reflects off the meteor and is suddenly audible to the remote station. Quickly, the remote station switches into transmission mode and bursts back with a shot of data to the place where the carrier tone came from. When the meteor trail dies down, the remote station goes back into receiving mode until it hears the carrier again.

The main problem with meteor burst is, the trails evaporate very quickly. A meteor trail lasts anywhere from a fifth of a second to one second, and then you've got to find another one. Fortunately, there's usually one in a few seconds, but it could take up to a few minutes until you have another window through which to burst information.

Amateur radio operators have been using "meteor scatter" since the 1950s. Without a huge base station, amateurs just alternate periods of transmitting and listening when they hear a meteor "ping," hoping their signal is reflected, said Shelby Ennis, a retired pastor in Kentucky who has been doing meteor scatter since 1955.

Meteor burst systems are able to get between 9,600 and 14,400 baud data transfer rates, experts said, much like modems from the mid-1990s. That's not enough for live video or voice. But it's fine for transmitting location data, the depth of snowpacks, simple messages or even limited e-mail.

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