Call it a close encounter -- of the cellular kind. Mike Cousins was making his daily drive up to the Dish one afternoon last fall when he spotted a hiker gabbing on a wireless phone. "I just suggested he not use it so close to our facility," says Cousins. "If the timing is right, it ruins the data."
Such are the pitfalls of operating the world's third-largest radio telescope amid some of the busiest airwaves in the country. Cousins, a program manager for SRI International, oversees the government-owned Dish on a hilltop above campus. The 35-year-old telescope has become increasingly popular among scientists and government agencies since it was restored to full operation 10 years ago. It's used for everything from calibrating satellites to measuring the expansion of the universe.
Now the trick is screening out the ever-increasing interference from radar, airplane transmissions, TV stations, pagers and cell phones. "There's no way to hide anymore, and it's getting worse," says Ivan Linscott, a senior research associate at STARLab, Stanford's Space Telecommunications and Radioscience Laboratory. Linscott and his colleagues have been developing software that isolates such phenomena as the faint pulsations of distant black holes received by the Dish. At least one PhD dissertation has been written on the so-called filters. "At its best," Linscott says, "this lets you get the kind of data you'd get from the back side of the moon" -- a location that, for now, is blissfully free of phone-toting hikers.
