Arecibo Reprise

After sleeping for 5 years in a mountaintop sinkhole, the world's most powerful radar and radio telescope--spiffed up after a $27 million upgrade--is about to spring back to life. In a ceremony tomorrow in Puerto Rico, technicians will power up the venerable Arecibo telescope so it can once again collect data from the heavens.

Unlike most telescopes with a movable reflector dish, Arecibo's enormous 305-meter-diameter dish is fixed in a crater. Instead of moving the reflector, astronomers can move the equipment that collects signals bouncing off the dish, allowing it to view different parts of the sky.

The old system had a series of "line feeds," instruments that sense a narrow range of frequencies, to detect information. The new system uses a pair of mirrors to steer the entire spectrum of electromagnetic radiation to a detector, giving researchers much broader access to the spectrum. "They operate over a very wide frequency range with low loss," says Paul Goldsmith, the director of Cornell's National Astronomy and Ionosphere Center, which operates the telescope. The upgrade increases the sensitivity of the telescope by a factor of 3 or so, and it can gather information at 10,000 MHz, instead of the old system's 3000 MHz.

The telescope also has a new million-watt radar transmitter, more than doubling its previous power. By bouncing radio waves off the dish and into the sky, the researchers can determine the shape of distant asteroids and planets in much the same way that a radar can identify planes. "Now it's 20 times more capable for radar astronomy," says Hugh Van Horn, director of the National Science Foundation's astronomy division, the biggest source of funding for the telescope. "You can study and map asteroids in near-Earth orbit, or the rings of Saturn."

The upgrade was marred by cost overruns and delays. "It was supposed to take 20 months; it took several years longer," says Goldsmith. "It put a great burden on the scientific community." The contractor that took on the Arecibo upgrade, Comsat RSI, is suing Cornell University for $7 million over cost overruns. Comsat RSI officials were unavailable for comment. No matter what the outcome, astronomers are anxious to start getting data again. "Little things need to be tweaked," says Van Horn. "But we should start seeing [scientific] observations in the fall."