THE EYES IN THE SKY KEEPING WATCH ON IRAQ
With high-powered telescopes and infrared sensors, U. S. satellites hover in orbits 22,500 miles high, searching for the telltale signs of missiles blasting off. Intended to spot Soviet launches, these Defense Support Program satellites (DSP) have joined the search for Iraqi Scud missiles. "This war is the first war where satellites are really making their mark in terms of support for battlefield operations," says Brookings Institution analyst Paul B. Stares.
But that's no easy task. To get maximum coverage of the earth's surface, the DSP's telescope revolves five to six times a minute. When it detects the heat from a rocket launch, the satellite transmits the information to an Air Force ground station in Alice Springs, Australia.
Within about 45 seconds, analysts evaluate the information and decide whether to pass it on to North American Aero space Defense Command (NORAD) in Colorado Springs, the only place where the final analysis can be made. "By the time the rocket plume is identified at NORAD, it is about two minutes after the launch," says Bruce G. Blair, an arms-control expert at Brookings. It takes another minute or two before the information is relayed back to the gulf. That leaves just enough time to provide a local warning of a minute or more before the missile strikes. The satellite data also furnish the launch-site location for prowling allied bombers. Meanwhile, the Patriot batteries use their own radars to detect and fireat Scuds.
The DSP is just part of the satellite fleet. According to space expert John Pike of the American Federation of Scientists, the U. S. has six so-called Keyhole satellites that use TV cameras with telescopes that can spot objects as small as six inches wide from their 150- to 250-mile-high orbits. Another satellite, the Lacrosse, has radar that can spy objects roughly the size of a jeep, even through clouds.
Still, there are major gaps in the coverage. Because of its orbit, the Lacrosse can spy into Iraq and Kuwait for only a few minutes per day. Some experts estimate that the periods when the Keyhole satellites can't see into Iraq are as long as five hours. And that's if skies are both clear and bright. When there's heavy cloud cover, most of the U. S. satellites with all their high-tech wizardry aren't much use to allied forces.John Carey in Washington