Shuttle Launch at the Mercy of Weather Report

With all systems looking good, space officials are to begin their official countdown this morning for the launch of the Discovery space shuttle Thursday morning.

But although the weather forecast is favorable, new weather restrictions will make it far more difficult to launch than in the past, raising the specter of seemingly endless delays in the nation’s return to the manned exploration of space.

The new restrictions grew out of the explosion of Challenger on Jan. 28, 1986, a disaster that was caused partly by weather, and the subsequent loss of an unmanned Atlas rocket launched during a thunderstorm here a few weeks later.

There is little room for maneuvering by launch officials because the rules will be binding.

“Prior to these changes, the rules were considered guidelines,” said Air Force Maj. Norman Buss, who is in charge of the forecasting facility here. “Now they are rules, and rules that are not to be waived.”

35% to 40% of the Time

Buss said that the new restrictions will prohibit the National Aeronautics and Space Administration from launching “35% to 40% of the time.”

That means about twice as many launch opportunites will be lost compared to the days before the Challenger exploded on a cold winter’s day here nearly three years ago.

After clearing away the last of the paper work, NASA was to issue the “call to stations” at 5 a.m. PDT, starting the clock ticking toward the launch. The call is little more than a roll call to see that everybody is in the right place.

The space agency had added 27 unprogrammed hours to the countdown as insurance for last-minute problems, and Robert B. Sieck, director of shuttle operations, said eight hours of that time would be used in advance to complete the work of replacing panels and work platforms.

“We don’t want those people to have to do that under the gun with the clock counting,” he said. “So we said, ‘take all the time it takes and we’ll delay the call to stations to accommodate that.”’

NASA had planned to start the countdown at midnight, but “buttoning up” the aft end of the spaceplane--akin to closing the hood on a car--was delayed by a problem that had the potential of postponing the launch for two days.

Low voltage readings were found in an electrical circuit that triggers the explosive charges used to separate the shuttle from its fuel tank when the tank is empty. Eventually engineers determined that the fault was in a ground circuit, which does not affect the flight.

A number of built-in “holds” are in the countdown to give technicians an occasional chance to catch up on their work and, if all goes according to plan, Discovery will blast off at 6:59 a.m. PDT Thursday. It is to land the following Monday morning at Edwards Air Force Base in Southern California.

There have been no serious problems with any of the hundreds of modifications made in the shuttle since the Challenger tragedy and officials here said they do not expect any.

“We’re looking for a launch on Thursday,” said Frank Merlino, NASA’s test director here.

Hurricane Cooperating

The good news is that even Hurricane Helene seems to be cooperating, staying so far away that officials see virtually no chance that it will pose a problem. The bad news is that it would only take a small thundershower to delay the launch.

A wide range of new weather “criteria” must be met before meteorologists can give their approval for launch and under the new rules the weather conditions are “considered violated until proven otherwise,” Buss said. In other words, the weather will be considered “guilty until proven innocent” and forecasters must be satisfied that none of the new limits will be exceeded, he said.

The weather data is collected from a wide range of sources--small weather rockets, scores of balloons, ground stations, a satellite and aircraft--that examine 12,000 cubic miles of atmosphere over Cape Canaveral. A small cloud that drifts over the area from a thunderstorm more than 100 miles away would be reason enough to delay the launch.

That does not mean that the sky must be perfectly clear because some clouds could be too thin or too high to produce lightning or rain that would jeopardize the flight, but it does mean that conditions have to be nearly perfect.

No Landing Power

Even cross winds of more than 12 knots (a 20% reduction over previous guidelines) would force a delay because in an emergency the shuttle might have to return immediately to the Kennedy landing strip and cross winds could pose a serious problem. The shuttle has no power during landing, which makes it a huge glider.

From a weather standpoint, the worst time of the year will be summer afternoons when thunderstorms rip across this part of the nation and winter days that frequently have high winds, Buss said.

Yet in spite of the tough new restrictions, officials here are eager to resume spaceflights and the fever is catching on all over central Florida. Green ribbons saying “Go Discovery” flutter from nearly every chest, and banners announcing an endless series of launch parties stream from every bar and restaurant along the entire “Space Coast.”

It has been a long time since a manned space vehicle lifted off from this historic setting.

On Thursday, a ship called Discovery could change that. At its command will be veteran astronaut Frederick H. Hauck, 47. The other members of the crew, all veterans, are Richard O. Covey, 42, the co-pilot; John M. Lounge, 42; David C. Hilmers, 38, and George D. Nelson, 38.

The primary goal of the four-day mission will be to launch a communications satellite for NASA and to prove that the Unites States is back in space--an enterprise it once dominated.