How computers use meteors to speed communication in remote places
Standing on a frozen mountainside in Idaho, an automatic weather station senses the rapidly gathering snow. People have to be warned: Floods might result in the valleys below.
No one can fetch this vital information, and the mountains are hostile to phone lines and ordinary radio.
Scanning the skies, the transmitter detects a cluster of pinhead-size meteors. Perfect. Instantly the device fires off thousands of bits of computerized information. They bounce off the meteor trails and speed back down to hydrologists more than a thousand miles away.
Such is the result of marrying sophisticated computers with garbage from outer space.
The system is called meteor burst communications and, while it has existed for years, in some uses it may replace satellites as an effective radio reflector in space.
* In the mountainous Northwest, the US Soil Conservation Service maintains a system of 475 rain and snow detectors in nine states. Every 15 minutes, the stations bounce the information off meteor trails to receivers in Idaho and Utah and to a master station in Oregon. Using this information, hydrologists can predict runoff and adjust the water level in reservoirs.
"The whole data transmission scheme takes less than a tenth of a second," says Lloyd Vancil, head electronics technician at the Soil Conservation Service in Portland. "It's cheap and easy to maintain."
* The Coast Guard may use meteor burst communications to keep tabs on the estimated 140,000 buoys in US coastal waters.
"It's one of the most viable options," said Stephen Jaskulek of The Johns Hopkins University applied physics laboratory, who is doing a feasibility study for the Coast Guard. "If you have to rent satellite time it can be very, very costly."
* Worried that other forms of communication can be knocked out in a war, the Defense Department has experimented with meteor burst communication from ground to airborne bombers. Some defense analysts have theorized that meteor burst might be a good communications fallback among atomic weapons facilities during a nuclear attack.
* A private firm called Telcom Inc. uses meteor bursts to transfer information between its Washington, D.C., area office and a branch office in Tennessee, more than 400 miles away.
Proponents tout meteor burst as easier than telephone, cheaper than satellites, and more reliable than radio. Although the system is not intended to carry the human voice, for the language of computers it is effective indeed.
The key to the system rests in the fact that billions of meteors burst through the atmosphere each day. Although most are barely the size of a pinhead , they're large enough to leave electronic ripples in the atmosphere, similar to a wake following a boat. Just as the ripples in the water reflect light, these electronic ripples reflect radio waves.
The trick is to locate these ripples to direct signals to them. It took the computer technology of the 1960s and '70s to do that. Scanning the skies, computerized transmitters lock in on a cluster of meteor trails and fire off their stored information in computer-language bits.
This pathway may seem indirect, but it's an excellent way to send information. The meteor trails are so high -- 60 to 80 miles above the surface -- that transmitters bouncing signals off them can communicate over separations of as much as 1,000 miles. The system is far cheaper than stringing telephone wires to out-of-the-way locations or renting satellite time for cross-country communications.
Last year the US Soil Conservation Service installed six stations around Mt. St. Helens to detect the moisture and temperature changes and alert people to impending floods. The system works far better than conventional radio, officials explain, because mountain peaks interfere with high frequency radio's line-of-site signal. It's more reliable than shortwave radio which, bouncing off the ionosphere, frequently is disturbed by sunspots or seasonal changes.
"There's a tremendous opportunity around the nation for this sort of system," said hydrologist Art Cook of the Soil Conservation Service in Portland. "We're fascinated by the opportunities."
Researchers have known since the 1920s that meteor trails reflect electronic signals. In the 1950s the National Bureau of Standards sent small bursts of information hundreds of miles across country by reflecting them off meteor trails. The Stanford Research Institute, the Hughes Aircraft Company, and the Canadian Defense Research Board performed similar experiments.
These tests showed meteor burst communications could work. But because most meteor trails last a mere fraction of a second, the information would have to be broadcast in ultrafast bursts -- something a computer is best suited to do.
In 1965 a NATO research group set up a computerized meteor burst communications link between Holland and France that still is working today. In fact, the technology would have become more widely used had not interest in communication satellites taken hold at roughly the same time.
"There was a lot of enthusiasm about satellite communication," explains Steven Jasculek of the Johns Hopkins applied physics lab. "It seemed the answer to everything."
Eventually, however, satellites became too popular: Users can be "bumped" from a satellite as higher priority messages go through.Defense analysts fear satellites will be the first targets as weapon development moves to outer space. Furthermore, the $3,000 to $4,000 meteor burst transmitters are simpler and easier to repair than their satellite-oriented counterparts.
However, reliable and inexpensive as it is, meteor burst communication has disadvantages that will keep it from common use. For reasons not completely known, in broadcasting to airplanes the signal can be disrupted by electronic "noise" drifting upward from cities. And a several-minute wait can result while computers search for the mercurial trails.
Experts say this makes the technology inappropriate for most voice communications. Indeed, it may best serve in the remote regions of the world where computers gathering information car fire back what they have learned in a tenth-of-a-second flash.