There are now 110 satellites in geosynchronous orbit, a narrow corridor 22,300 miles above the equator where man-made moons can hover in such a way that they remain in the same spot above the Earth's surface. The corridor is advantageous for telecommunications and weather forcasting, and hundreds of new satellites are planned for launch in the next decade. Now 12 of the 21 choice geosynchronous locations in the western hemisphere are occupied by American and Canadian satellites, and both countries, as well as some in Latin America, are making plans to take the remaining parking places. "It's the sweet spot," says an official of the National Aeronautics and Space Administration. "It's where everybody, including the military, wants to be." Satellites in geosynchronous orbit have a tendency to jam one another's radio transmissions, and this has forced scientists to park them about 1,500 miles apart to avoid interference. Ron Lepkowski, chief of the satellite radio branch for the Federal Communications Commission, says the easiest way to accommodate more satellites is to park them closer together, but that could reduce the transmission levels of existing ones.

"The level of interference would increase," says Lepkowski. "We're trying to determine if it would be an intolerable level, or if satellite owners could live with it." Using different radio frequencies so neighboring satellites won't interfere with each other is another possibility, he said, but that could also cause problems.

"It's more expensive to use the new band, and it can be shut down by rain," says Sam Fordyze, program manager of the comunications division at NASA headquarters.