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U.S. Forecasters Awaiting Extra Eye in the Sky : Meteorology: The U.S. has been down to one satellite to keep watch on a continent of violent weather. A German craft will help out for a while.


WALLOPS ISLAND, Va. — Government weather watchers on this sandy Delmarva Peninsula ridge eagerly await an aging European satellite that should help nervous forecasters breathe a little easier.

By January the German weather satellite, Meteosat-3, will be relocated in space to provide better weather coverage of the United States while a new U.S. satellite is being readied.

New equipment being installed here at National Oceanic and Atmospheric Administration facilities will transmit the spacecraft's data and weather pictures for at least a year.

Forecasters have been uneasy because the United States has only one of its own 5-year-old weather satellites, GOES-7, in orbit--and it is living on borrowed time.

Unsung space heroes, NOAA's GOES (geostationary operational environmental satellites) have kept a vigilant eye peeled for violent weather, such as the hurricanes that lashed Florida and Hawaii.

The spacecraft have saved lives and millions of dollars with their wide-ranging views of violent conditions, enabling forecasters to predict where they will hit, often days in advance. The satellites produce the weather pictures seen in newspapers and on television.

The United States once kept two GOES satellites aloft, but one blew up in a failed 1986 launch and another stopped functioning in January, 1989, leaving only GOES-7 in orbit.

The first in a $1.7-billion new generation of five satellites known as GOES-NEXT, won't be operational until 1994 at the earliest.

So European space organizations have come to the rescue and will nudge their Meteosat-3 satellite closer to the United States, while GOES-7 will be shifted farther west for a better view of the central Pacific.

In a sense the Europeans are repaying a favor, at no cost to NOAA. The United States lent them a satellite, without charge, when one of theirs was in trouble in the mid-1980s.

"If GOES-7 were to fail now, the West Coast of the United States and the eastern Pacific both would be in pretty bad shape from the point of dynamic viewing," says E. Larry Heacock, director of NOAA's office of satellite operations.

Perched in a 22,300-mile-high stationary orbit that matches the rotation of the planet, the GOES and Meteosat spacecraft send back continuous images.

"Barring an unexpected catastrophic failure, GOES-7 should produce usable products through 1994," says Thomas N. Pyke Jr., assistant administrator for NOAA's satellite and information service.

Still, meteorologists are edgy, even though negotiations are under way with the Europeans for another Meteosat backup if it should be needed.

"The GOES-7 spacecraft is healthy, but it's the only one we have now that provides solid overall coverage," Joe Friday, director of the National Weather Service, says. "Meteosat-3 is providing us with good data but is also about the same age. And so we're nervous."

If both GOES and Meteosat failed at the same time, U.S. forecasters would have to rely on four polar-orbiting weather satellites, two operated by NOAA and two by the Defense Department.

Because they circle the Earth instead of staying in a fixed position, the polar orbiters provide periodic pictures and not the continuous coverage that experts need to track and predict the direction of storms. It's like working with snapshots instead of a movie.

At the National Hurricane Center in Miami, tests have simulated a no-GOES scenario. "There are big problems with the polar-orbiting data because it's not very timely," says Director Robert C. Sheets. "Sometimes you may be working with 6-hour-old data."

Without its trusted weather eyes, the center would keep storm-tracking aircraft busier than usual, especially during hurricane season. "We're averaging about 1,500 hours of flight time a year; I could see that going to 6,000 hours," Sheets says.

A GOES-7 failure would mean more than a loss of pictures. An experimental instrument on the satellite that will be standard equipment on GOES-NEXT has been transmitting valuable information on temperature and humidity changes in the Earth's atmosphere.

"This is particularly important in the vicinity of severe storm complexes and hurricanes, because it's those rapid changes that give us the indication of the way storms are moving or developing," Friday says.

Long-range weather forecasting may be improved by an international venture involving a Franco-American satellite that recently was launched by Arianespace, a European consortium.

Instruments on the satellite, Topex-Poseidon, are expected to yield new information on ocean currents and global heat transmission, key components of the forces that determine the world's weather, and eventually could extend three-day forecasts to as much as a week.

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